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[compiler-rt][nsan] Add check-cmp flag (#108707)

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Add check-cmp flag.

Closes #108435.
This commit is contained in:
c8ef
2024-09-24 09:49:36 +08:00
committed by GitHub
parent 6bed79b3f0
commit 86c6403232
3 changed files with 34 additions and 3 deletions
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4
compiler-rt/lib/nsan/nsan.cpp
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@@ -25,7 +25,7 @@
// on the runtime configuration. The middle part indicates the type of
// the application value, the suffix (f,d,l) indicates the type of the
// shadow, and depends on the instrumentation configuration.
// * __nsan_fcmp_fail_* emits a warning for an fcmp instruction whose
// * __nsan_fcmp_fail_* emits a warning for a fcmp instruction whose
// corresponding shadow fcmp result differs.
//
//===----------------------------------------------------------------------===//
@@ -682,7 +682,7 @@ void fCmpFailFT(const FT Lhs, const FT Rhs, ShadowFT LhsShadow,
if (flags().enable_warning_stats)
nsan_stats->AddWarning(CheckTypeT::kFcmp, pc, bp, 0.0);
if (flags().disable_warnings)
if (flags().disable_warnings || !flags().check_cmp)
return;
// FIXME: ideally we would print the shadow value as FP128. Right now because

3
compiler-rt/lib/nsan/nsan_flags.inc
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@@ -50,3 +50,6 @@ NSAN_FLAG(bool, poison_in_free, true, "")
NSAN_FLAG(bool, print_stats_on_exit, false, "If true, print stats on exit.")
NSAN_FLAG(bool, check_nan, false,
"If true, check the floating-point number is nan")
NSAN_FLAG(bool, check_cmp, true,
"If true, emit a warning for a fcmp instruction whose "
"corresponding shadow fcmp result differs.")

28
compiler-rt/test/nsan/fcmp.cpp Normal file
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@@ -0,0 +1,28 @@
// RUN: %clangxx_nsan -O2 -g %s -o %t
// RUN: env NSAN_OPTIONS=check_cmp=true,halt_on_error=0 %run %t 2>&1 | FileCheck %s -check-prefix=CMP_ENABLE
// RUN: env NSAN_OPTIONS=check_cmp=false,halt_on_error=0 %run %t 2>&1 | FileCheck %s -check-prefix=CMP_DISABLE
#include <cmath>
#include <cstdio>
// 0.6/0.2 is slightly below 3, so the comparison will fail after a certain
// threshold that depends on the precision of the computation.
__attribute__((noinline)) // To check call stack reporting.
bool DoCmp(double a, double b, double c, double threshold) {
return c - a / b < threshold;
// CMP_ENABLE: WARNING: NumericalStabilitySanitizer: floating-point comparison results depend on precision
// CMP_ENABLE: double {{ *}}precision dec (native): {{.*}}<{{.*}}
// CMP_ENABLE: __float128{{ *}}precision dec (shadow): {{.*}}<{{.*}}
// CMP_ENABLE: {{#0 .*in DoCmp}}
}
int main() {
double threshold = 1.0;
for (int i = 0; i < 60; ++i) {
threshold /= 2;
// CMP_DISABLE: value at threshold {{.*}}
printf("value at threshold %.20f: %i\n", threshold,
DoCmp(0.6, 0.2, 3.0, threshold));
}
return 0;
}