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

[vitalybuka]

Summary

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.

[vitalybuka]

llvm/test/Instrumentation/MemorySanitizer/create-class-from-logic-fcmp.ll

4 ↗

(On Diff #518067)

Maybe better to move into original create-class-from-logic-fcmp.ll ?

[vitalybuka]

fix condition

[vitalybuka]

simplify test

[vitalybuka]

rebase

llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp

void handleAbsIntrinsic(IntrinsicInst &I) {
     assert(I.getArgOperand(0)->getType() == I.getType());
 
     // FIXME: Handle is_int_min_poison.
     IRBuilder<> IRB(&I);
     setShadow(&I, getShadow(&I, 0));
     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;
     case Intrinsic::launder_invariant_group:
     case Intrinsic::strip_invariant_group:
       handleInvariantGroup(I);
       break;
     case Intrinsic::bswap:

llvm/test/Instrumentation/MemorySanitizer/is-fpclass.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -S -passes=msan < %s | FileCheck %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 ; Function Attrs: sanitize_memory
 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)
   ret i1 %class
 }
 
 ; Function Attrs: sanitize_memory
 define <2 x i1> @not_isfinite_or_zero_v2f16_pos0_neg0_vec(<2 x half> %x) sanitize_memory {
 ; 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)
   ret <2 x i1> %class
 }
 
 ; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
 declare i1 @llvm.is.fpclass.f16(half, i32 immarg) #1
 
 ; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
 declare <2 x i1> @llvm.is.fpclass.v2f16(<2 x half>, i32 immarg) #1