[llvm] 67caff6 - [msan] Improve handling of Intrinsic::is_fpclass after c55fffe

[Vitaly Buka via llvm-commits]

Author: Vitaly Buka
Date: 2023-04-28T16:27:31-07:00
New Revision: 67caff6f32bd7846bf2fe9310a789c6729939f37

URL: https://github.com/llvm/llvm-project/commit/67caff6f32bd7846bf2fe9310a789c6729939f37
DIFF: https://github.com/llvm/llvm-project/commit/67caff6f32bd7846bf2fe9310a789c6729939f37.diff

LOG: [msan] Improve handling of Intrinsic::is_fpclass after c55fffe

c55fffe replaced fcmp with fpclass.

```
declare i1 @llvm.is.fpclass(<fptype> <op>, i32 <test>)
declare <N x i1> @llvm.is.fpclass(<vector-fptype> <op>, i32 <test>)
```

Perfect fix will require checking bits of <op> corresponding to <test>
argument. For now just propagate shadow without reporting before
intrinsic. Still existing handling of fcmp is also simple OR, so it's
not making it worse.

Reviewed By: eugenis

Differential Revision: https://reviews.llvm.org/D149491

Added: 
    

Modified: 
    llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
    llvm/test/Instrumentation/MemorySanitizer/is-fpclass.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index e2269c2a8638d..3341615219185 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -3702,11 +3702,21 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
     setOrigin(&I, getOrigin(&I, 0));
   }
 
+  void handleIsFpClass(IntrinsicInst &I) {
+    IRBuilder<> IRB(&I);
+    Value *Shadow = getShadow(&I, 0);
+    setShadow(&I, IRB.CreateICmpNE(Shadow, getCleanShadow(Shadow)));
+    setOrigin(&I, getOrigin(&I, 0));
+  }
+
   void visitIntrinsicInst(IntrinsicInst &I) {
     switch (I.getIntrinsicID()) {
     case Intrinsic::abs:
       handleAbsIntrinsic(I);
       break;
+    case Intrinsic::is_fpclass:
+      handleIsFpClass(I);
+      break;
     case Intrinsic::lifetime_start:
       handleLifetimeStart(I);
       break;

diff  --git a/llvm/test/Instrumentation/MemorySanitizer/is-fpclass.ll b/llvm/test/Instrumentation/MemorySanitizer/is-fpclass.ll
index 3324cf0b0397d..e3467d8da3011 100644
--- a/llvm/test/Instrumentation/MemorySanitizer/is-fpclass.ll
+++ b/llvm/test/Instrumentation/MemorySanitizer/is-fpclass.ll
@@ -9,14 +9,9 @@ define i1 @not_isfinite_or_zero_f16(half %x) sanitize_memory {
 ; CHECK-LABEL: @not_isfinite_or_zero_f16(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i16, ptr @__msan_param_tls, align 8
 ; CHECK-NEXT:    call void @llvm.donothing()
-; CHECK-NEXT:    [[_MSCMP:%.*]] = icmp ne i16 [[TMP1]], 0
-; CHECK-NEXT:    br i1 [[_MSCMP]], label [[TMP2:%.*]], label [[TMP3:%.*]], !prof [[PROF0:![0-9]+]]
-; CHECK:       2:
-; CHECK-NEXT:    call void @__msan_warning_noreturn() #[[ATTR4:[0-9]+]]
-; CHECK-NEXT:    unreachable
-; CHECK:       3:
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp ne i16 [[TMP1]], 0
 ; CHECK-NEXT:    [[CLASS:%.*]] = call i1 @llvm.is.fpclass.f16(half [[X:%.*]], i32 615)
-; CHECK-NEXT:    store i1 false, ptr @__msan_retval_tls, align 8
+; CHECK-NEXT:    store i1 [[TMP2]], ptr @__msan_retval_tls, align 8
 ; CHECK-NEXT:    ret i1 [[CLASS]]
 ;
   %class = call i1 @llvm.is.fpclass.f16(half %x, i32 615)
@@ -28,15 +23,9 @@ define <2 x i1> @not_isfinite_or_zero_v2f16_pos0_neg0_vec(<2 x half> %x) sanitiz
 ; CHECK-LABEL: @not_isfinite_or_zero_v2f16_pos0_neg0_vec(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load <2 x i16>, ptr @__msan_param_tls, align 8
 ; CHECK-NEXT:    call void @llvm.donothing()
-; CHECK-NEXT:    [[TMP2:%.*]] = bitcast <2 x i16> [[TMP1]] to i32
-; CHECK-NEXT:    [[_MSCMP:%.*]] = icmp ne i32 [[TMP2]], 0
-; CHECK-NEXT:    br i1 [[_MSCMP]], label [[TMP3:%.*]], label [[TMP4:%.*]], !prof [[PROF0]]
-; CHECK:       3:
-; CHECK-NEXT:    call void @__msan_warning_noreturn() #[[ATTR4]]
-; CHECK-NEXT:    unreachable
-; CHECK:       4:
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp ne <2 x i16> [[TMP1]], zeroinitializer
 ; CHECK-NEXT:    [[CLASS:%.*]] = call <2 x i1> @llvm.is.fpclass.v2f16(<2 x half> [[X:%.*]], i32 615)
-; CHECK-NEXT:    store <2 x i1> zeroinitializer, ptr @__msan_retval_tls, align 8
+; CHECK-NEXT:    store <2 x i1> [[TMP2]], ptr @__msan_retval_tls, align 8
 ; CHECK-NEXT:    ret <2 x i1> [[CLASS]]
 ;
   %class = call <2 x i1> @llvm.is.fpclass.v2f16(<2 x half> %x, i32 615)