[msan] Don't check divisor shadow in fdiv.
Summary:
Floating point division by zero or even undef does not have undefined
behavior and may occur due to optimizations.
Fixes https://bugs.llvm.org/show_bug.cgi?id=37523.
Reviewers: kcc
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D47085
llvm-svn: 332761
diff --git a/compiler-rt/lib/msan/tests/msan_test.cc b/compiler-rt/lib/msan/tests/msan_test.cc
index 7a582c9..fd3973b 100644
--- a/compiler-rt/lib/msan/tests/msan_test.cc
+++ b/compiler-rt/lib/msan/tests/msan_test.cc
@@ -4044,7 +4044,6 @@
typedef U2 V4x16 __attribute__((__vector_size__(8)));
typedef U1 V8x8 __attribute__((__vector_size__(8)));
-
V8x16 shift_sse2_left_scalar(V8x16 x, U4 y) {
return _mm_slli_epi16(x, y);
}
diff --git a/compiler-rt/test/msan/vector_div.cc b/compiler-rt/test/msan/vector_div.cc
new file mode 100644
index 0000000..4ca2369
--- /dev/null
+++ b/compiler-rt/test/msan/vector_div.cc
@@ -0,0 +1,17 @@
+// Regression test for https://bugs.llvm.org/show_bug.cgi?id=37523
+
+// RUN: %clangxx_msan -O0 %s -o %t && %run %t
+// RUN: %clangxx_msan -O3 %s -o %t && %run %t
+// REQUIRES: x86_64-target-arch
+
+#include <assert.h>
+#include <emmintrin.h>
+
+int main() {
+ volatile int scale = 5;
+ volatile auto zz = _mm_div_ps(_mm_set1_ps(255), _mm_set1_ps(scale));
+ assert(zz[0] == 51);
+ assert(zz[1] == 51);
+ assert(zz[2] == 51);
+ assert(zz[3] == 51);
+}
diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index eb2af4f..5fbb651 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -1841,7 +1841,7 @@
void visitSub(BinaryOperator &I) { handleShadowOr(I); }
void visitXor(BinaryOperator &I) { handleShadowOr(I); }
- void handleDiv(Instruction &I) {
+ void handleIntegerDiv(Instruction &I) {
IRBuilder<> IRB(&I);
// Strict on the second argument.
insertShadowCheck(I.getOperand(1), &I);
@@ -1849,12 +1849,15 @@
setOrigin(&I, getOrigin(&I, 0));
}
- void visitUDiv(BinaryOperator &I) { handleDiv(I); }
- void visitSDiv(BinaryOperator &I) { handleDiv(I); }
- void visitFDiv(BinaryOperator &I) { handleDiv(I); }
- void visitURem(BinaryOperator &I) { handleDiv(I); }
- void visitSRem(BinaryOperator &I) { handleDiv(I); }
- void visitFRem(BinaryOperator &I) { handleDiv(I); }
+ void visitUDiv(BinaryOperator &I) { handleIntegerDiv(I); }
+ void visitSDiv(BinaryOperator &I) { handleIntegerDiv(I); }
+ void visitURem(BinaryOperator &I) { handleIntegerDiv(I); }
+ void visitSRem(BinaryOperator &I) { handleIntegerDiv(I); }
+
+ // Floating point division is side-effect free. We can not require that the
+ // divisor is fully initialized and must propagate shadow. See PR37523.
+ void visitFDiv(BinaryOperator &I) { handleShadowOr(I); }
+ void visitFRem(BinaryOperator &I) { handleShadowOr(I); }
/// Instrument == and != comparisons.
///
diff --git a/llvm/test/Instrumentation/MemorySanitizer/msan_basic.ll b/llvm/test/Instrumentation/MemorySanitizer/msan_basic.ll
index 0c23ede..1f412ff 100644
--- a/llvm/test/Instrumentation/MemorySanitizer/msan_basic.ll
+++ b/llvm/test/Instrumentation/MemorySanitizer/msan_basic.ll
@@ -417,6 +417,21 @@
; CHECK-NOT: icmp
; CHECK: ret i32
+; Check that fdiv, unlike udiv, simply propagates shadow.
+
+define float @FDiv(float %a, float %b) nounwind uwtable readnone sanitize_memory {
+entry:
+ %c = fdiv float %a, %b
+ ret float %c
+}
+
+; CHECK-LABEL: @FDiv
+; CHECK: %[[SA:.*]] = load i32,{{.*}}@__msan_param_tls
+; CHECK: %[[SB:.*]] = load i32,{{.*}}@__msan_param_tls
+; CHECK: %[[SC:.*]] = or i32 %[[SB]], %[[SA]]
+; CHECK: = fdiv float
+; CHECK: store i32 %[[SC]], i32* {{.*}}@__msan_retval_tls
+; CHECK: ret float
; Check that we propagate shadow for x<0, x>=0, etc (i.e. sign bit tests)
