lib: cbprintf: work around LLVM code generation bug
LLVM building for qemu_x86 appears to have an optimization bug where a union that is assigned to hold values read from va_args() is inferred to be a constant value, so is placed in ROM with an all-zero content. Prevent this by packing the conversion state and the value union into a single container structure that's stack allocated. Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
This commit is contained in:
Peter Bigot
Carles Cufí
parent
f0250d5c71
commit
c1b0cf8ec6
1 changed files with 81 additions and 70 deletions
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@ -1393,57 +1393,69 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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continue;
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}
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/* Force union into RAM with conversion state to
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* mitigate LLVM code generation bug.
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*/
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struct {
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union argument_value value;
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struct conversion conv;
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} state = {
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.value = {
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.uint = 0,
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},
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};
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struct conversion *const conv = &state.conv;
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union argument_value *const value = &state.value;
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const char *sp = fp;
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struct conversion conv;
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int width = -1;
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int precision = -1;
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const char *bps = NULL;
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const char *bpe = buf + sizeof(buf);
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char sign = 0;
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fp = extract_conversion(&conv, sp);
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fp = extract_conversion(conv, sp);
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/* If dynamic width is specified, process it,
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* otherwise set with if present.
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*/
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if (conv.width_star) {
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if (conv->width_star) {
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width = va_arg(ap, int);
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if (width < 0) {
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conv.flag_dash = true;
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conv->flag_dash = true;
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width = -width;
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}
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} else if (conv.width_present) {
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width = conv.width_value;
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} else if (conv->width_present) {
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width = conv->width_value;
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}
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/* If dynamic precision is specified, process it, otherwise
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* set precision if present. For floating point where
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* precision is not present use 6.
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*/
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if (conv.prec_star) {
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if (conv->prec_star) {
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int arg = va_arg(ap, int);
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if (arg < 0) {
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conv.prec_present = false;
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conv->prec_present = false;
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} else {
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precision = arg;
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}
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} else if (conv.prec_present) {
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precision = conv.prec_value;
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} else if (conv->prec_present) {
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precision = conv->prec_value;
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}
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/* Reuse width and precision memory in conv for value
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* padding counts.
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*/
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conv.pad0_value = 0;
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conv.pad0_pre_exp = 0;
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conv->pad0_value = 0;
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conv->pad0_pre_exp = 0;
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/* FP conversion requires knowing the precision. */
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if (IS_ENABLED(CONFIG_CBPRINTF_FP_SUPPORT)
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&& (conv.specifier_cat == SPECIFIER_FP)
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&& !conv.prec_present) {
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if (conv.specifier_a) {
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&& (conv->specifier_cat == SPECIFIER_FP)
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&& !conv->prec_present) {
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if (conv->specifier_a) {
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precision = FRACTION_HEX;
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} else {
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precision = 6;
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@ -1457,12 +1469,9 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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* https://stackoverflow.com/a/8048892.
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*/
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enum specifier_cat_enum specifier_cat
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= (enum specifier_cat_enum)conv.specifier_cat;
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= (enum specifier_cat_enum)conv->specifier_cat;
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enum length_mod_enum length_mod
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= (enum length_mod_enum)conv.length_mod;
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union argument_value value = (union argument_value){
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.uint = 0,
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};
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= (enum length_mod_enum)conv->length_mod;
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/* Extract the value based on the argument category and length.
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*
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@ -1475,17 +1484,17 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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case LENGTH_NONE:
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case LENGTH_HH:
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case LENGTH_H:
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value.sint = va_arg(ap, int);
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value->sint = va_arg(ap, int);
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break;
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case LENGTH_L:
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value.sint = va_arg(ap, long);
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value->sint = va_arg(ap, long);
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break;
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case LENGTH_LL:
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value.sint =
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value->sint =
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(sint_value_type)va_arg(ap, long long);
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break;
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case LENGTH_J:
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value.sint =
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value->sint =
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(sint_value_type)va_arg(ap, intmax_t);
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break;
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case LENGTH_Z: /* size_t */
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@ -1497,14 +1506,14 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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* other. This can be checked in a platform
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* test.
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*/
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value.sint =
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value->sint =
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(sint_value_type)va_arg(ap, ptrdiff_t);
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break;
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}
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if (length_mod == LENGTH_HH) {
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value.sint = (char)value.sint;
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value->sint = (char)value->sint;
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} else if (length_mod == LENGTH_H) {
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value.sint = (short)value.sint;
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value->sint = (short)value->sint;
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}
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} else if (specifier_cat == SPECIFIER_UINT) {
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switch (length_mod) {
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@ -1512,40 +1521,40 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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case LENGTH_NONE:
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case LENGTH_HH:
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case LENGTH_H:
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value.uint = va_arg(ap, unsigned int);
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value->uint = va_arg(ap, unsigned int);
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break;
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case LENGTH_L:
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value.uint = va_arg(ap, unsigned long);
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value->uint = va_arg(ap, unsigned long);
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break;
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case LENGTH_LL:
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value.uint =
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value->uint =
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(uint_value_type)va_arg(ap,
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unsigned long long);
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break;
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case LENGTH_J:
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value.uint =
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value->uint =
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(uint_value_type)va_arg(ap,
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uintmax_t);
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break;
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case LENGTH_Z: /* size_t */
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case LENGTH_T: /* ptrdiff_t */
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value.uint =
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value->uint =
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(uint_value_type)va_arg(ap, size_t);
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break;
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}
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if (length_mod == LENGTH_HH) {
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value.uint = (unsigned char)value.uint;
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value->uint = (unsigned char)value->uint;
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} else if (length_mod == LENGTH_H) {
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value.uint = (unsigned short)value.uint;
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value->uint = (unsigned short)value->uint;
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}
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} else if (specifier_cat == SPECIFIER_FP) {
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if (length_mod == LENGTH_UPPER_L) {
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value.ldbl = va_arg(ap, long double);
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value->ldbl = va_arg(ap, long double);
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} else {
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value.dbl = va_arg(ap, double);
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value->dbl = va_arg(ap, double);
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}
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} else if (specifier_cat == SPECIFIER_PTR) {
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value.ptr = va_arg(ap, void *);
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value->ptr = va_arg(ap, void *);
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}
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/* We've now consumed all arguments related to this
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@ -1553,7 +1562,7 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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* something we don't support, then output the original
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* specification and move on.
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*/
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if (conv.invalid || conv.unsupported) {
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if (conv->invalid || conv->unsupported) {
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OUTS(sp, fp);
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continue;
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}
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@ -1561,12 +1570,12 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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/* Do formatting, either into the buffer or
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* referencing external data.
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*/
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switch (conv.specifier) {
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switch (conv->specifier) {
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case '%':
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OUTC('%');
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break;
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case 's': {
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bps = (const char *)value.ptr;
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bps = (const char *)value->ptr;
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size_t len = strlen(bps);
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@ -1582,20 +1591,22 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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}
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case 'c':
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bps = buf;
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buf[0] = value.uint;
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buf[0] = value->uint;
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bpe = buf + 1;
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break;
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case 'd':
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case 'i':
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if (conv.flag_plus) {
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if (conv->flag_plus) {
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sign = '+';
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} else if (conv.flag_space) {
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} else if (conv->flag_space) {
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sign = ' ';
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}
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if (value.sint < 0) {
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if (value->sint < 0) {
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sign = '-';
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value.uint = -value.sint;
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value->uint = (uint_value_type)-value->sint;
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} else {
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value->uint = (uint_value_type)value->sint;
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}
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__fallthrough;
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@ -1603,7 +1614,7 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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case 'u':
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case 'x':
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case 'X':
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bps = encode_uint(value.uint, &conv, buf, bpe);
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bps = encode_uint(value->uint, conv, buf, bpe);
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prec_int_pad0:
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/* Update pad0 values based on precision and converted
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@ -1617,11 +1628,11 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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/* Zero-padding flag is ignored for integer
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* conversions with precision.
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*/
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conv.flag_zero = false;
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conv->flag_zero = false;
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/* Set pad0_value to satisfy precision */
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if (len < (size_t)precision) {
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conv.pad0_value = precision - (int)len;
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conv->pad0_value = precision - (int)len;
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}
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}
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@ -1631,13 +1642,13 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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* has 0x prefix followed by significant address hex
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* digits, no leading zeros.
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*/
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if (value.ptr != NULL) {
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bps = encode_uint((uintptr_t)value.ptr, &conv,
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if (value->ptr != NULL) {
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bps = encode_uint((uintptr_t)value->ptr, conv,
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buf, bpe);
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/* Use 0x prefix */
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conv.altform_0c = true;
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conv.specifier = 'x';
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conv->altform_0c = true;
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conv->specifier = 'x';
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goto prec_int_pad0;
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}
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@ -1648,14 +1659,14 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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break;
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case 'n':
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if (IS_ENABLED(CONFIG_CBPRINTF_N_SPECIFIER)) {
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store_count(&conv, value.ptr, count);
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store_count(conv, value->ptr, count);
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}
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break;
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case FP_CONV_CASES:
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if (IS_ENABLED(CONFIG_CBPRINTF_FP_SUPPORT)) {
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bps = encode_float(value.dbl, &conv, precision,
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bps = encode_float(value->dbl, conv, precision,
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&sign, buf, &bpe);
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}
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break;
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@ -1694,15 +1705,15 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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nj_len += 1U;
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}
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if (conv.altform_0c) {
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if (conv->altform_0c) {
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nj_len += 2U;
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} else if (conv.altform_0) {
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} else if (conv->altform_0) {
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nj_len += 1U;
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}
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nj_len += conv.pad0_value;
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if (conv.pad_fp) {
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nj_len += conv.pad0_pre_exp;
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nj_len += conv->pad0_value;
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if (conv->pad_fp) {
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nj_len += conv->pad0_pre_exp;
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}
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/* If we have a width update width to hold the padding we need
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@ -1715,13 +1726,13 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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if (width > 0) {
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width -= (int)nj_len;
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if (!conv.flag_dash) {
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if (!conv->flag_dash) {
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char pad = ' ';
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/* If we're zero-padding we have to emit the
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* sign first.
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*/
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if (conv.flag_zero) {
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if (conv->flag_zero) {
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if (sign != 0) {
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OUTC(sign);
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sign = 0;
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@ -1742,10 +1753,10 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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OUTC(sign);
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}
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if (IS_ENABLED(CONFIG_CBPRINTF_FP_SUPPORT) && conv.pad_fp) {
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if (IS_ENABLED(CONFIG_CBPRINTF_FP_SUPPORT) && conv->pad_fp) {
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const char *cp = bps;
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if (conv.specifier_a) {
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if (conv->specifier_a) {
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/* Only padding is pre_exp */
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while (*cp != 'p') {
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OUTC(*cp++);
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@ -1755,8 +1766,8 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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OUTC(*cp++);
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}
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pad_len = conv.pad0_value;
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if (!conv.pad_postdp) {
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pad_len = conv->pad0_value;
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if (!conv->pad_postdp) {
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while (pad_len-- > 0) {
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OUTC('0');
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}
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@ -1776,22 +1787,22 @@ int cbvprintf(cbprintf_cb out, void *ctx, const char *fp, va_list ap)
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}
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}
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pad_len = conv.pad0_pre_exp;
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pad_len = conv->pad0_pre_exp;
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while (pad_len-- > 0) {
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OUTC('0');
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}
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OUTS(cp, bpe);
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} else {
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if (conv.altform_0c | conv.altform_0) {
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if (conv->altform_0c | conv->altform_0) {
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OUTC('0');
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}
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if (conv.altform_0c) {
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OUTC(conv.specifier);
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if (conv->altform_0c) {
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OUTC(conv->specifier);
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}
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pad_len = conv.pad0_value;
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pad_len = conv->pad0_value;
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while (pad_len-- > 0) {
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OUTC('0');
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}
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