[compiler-rt] 86c6403 - [compiler-rt][nsan] Add check-cmp flag (#108707)
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Mon Sep 23 18:49:40 PDT 2024
Author: c8ef
Date: 2024-09-23T18:49:36-07:00
New Revision: 86c640323286f4d692a634373c71536795cd7290
URL: https://github.com/llvm/llvm-project/commit/86c640323286f4d692a634373c71536795cd7290
DIFF: https://github.com/llvm/llvm-project/commit/86c640323286f4d692a634373c71536795cd7290.diff
LOG: [compiler-rt][nsan] Add check-cmp flag (#108707)
Add check-cmp flag.
Closes #108435.
Added:
compiler-rt/test/nsan/fcmp.cpp
Modified:
compiler-rt/lib/nsan/nsan.cpp
compiler-rt/lib/nsan/nsan_flags.inc
Removed:
################################################################################
diff --git a/compiler-rt/lib/nsan/nsan.cpp b/compiler-rt/lib/nsan/nsan.cpp
index 4679bcd589eb45..1c06340549acae 100644
--- a/compiler-rt/lib/nsan/nsan.cpp
+++ b/compiler-rt/lib/nsan/nsan.cpp
@@ -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
diff ers.
//
//===----------------------------------------------------------------------===//
@@ -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
diff --git a/compiler-rt/lib/nsan/nsan_flags.inc b/compiler-rt/lib/nsan/nsan_flags.inc
index 7c9e579d91fc33..760973295a8a50 100644
--- a/compiler-rt/lib/nsan/nsan_flags.inc
+++ b/compiler-rt/lib/nsan/nsan_flags.inc
@@ -49,4 +49,7 @@ NSAN_FLAG(bool, enable_loadtracking_stats, false,
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")
\ No newline at end of file
+ "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
diff ers.")
diff --git a/compiler-rt/test/nsan/fcmp.cpp b/compiler-rt/test/nsan/fcmp.cpp
new file mode 100644
index 00000000000000..e9ec84e05221dc
--- /dev/null
+++ b/compiler-rt/test/nsan/fcmp.cpp
@@ -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;
+}
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