[llvm-branch-commits] [llvm] 22dab21 - Revert "[SelectionDAG] Remove unused FP constant in getNegatedExpression"

[Hans Wennborg via llvm-branch-commits]

Author: Qiu Chaofan
Date: 2020-09-15T16:57:03+02:00
New Revision: 22dab218407e159631fd0689cb4412646b51515a

URL: https://github.com/llvm/llvm-project/commit/22dab218407e159631fd0689cb4412646b51515a
DIFF: https://github.com/llvm/llvm-project/commit/22dab218407e159631fd0689cb4412646b51515a.diff

LOG: Revert "[SelectionDAG] Remove unused FP constant in getNegatedExpression"

2508ef01 doesn't totally fix the issue since we did not handle the case
when unused temporary negated result is the same with the result, which
is found by address sanitizer.

(cherry picked from commit e1669843f2aaf1e4929afdd8f125c14536d27664)

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

Removed: 
    llvm/test/CodeGen/X86/pr47517.ll


################################################################################
diff  --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 4ebb99c97841..819e608c6896 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -5751,10 +5751,8 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG,
 
     // If we already have the use of the negated floating constant, it is free
     // to negate it even it has multiple uses.
-    if (!Op.hasOneUse() && CFP.use_empty()) {
-      RemoveDeadNode(CFP);
+    if (!Op.hasOneUse() && CFP.use_empty())
       break;
-    }
     Cost = NegatibleCost::Neutral;
     return CFP;
   }

diff  --git a/llvm/test/CodeGen/X86/pr47517.ll b/llvm/test/CodeGen/X86/pr47517.ll
deleted file mode 100644
index 6b508acf15dd..000000000000
--- a/llvm/test/CodeGen/X86/pr47517.ll
+++ /dev/null
@@ -1,28 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple x86_64 < %s | FileCheck %s
-
-; To ensure unused floating point constant is removed in negation
-define float @test(float %src, float* %p) {
-; CHECK-LABEL: test:
-; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    movq $0, (%rdi)
-; CHECK-NEXT:    xorps %xmm0, %xmm0
-; CHECK-NEXT:    retq
-entry:
-  %a0 = getelementptr inbounds float, float* %p, i32 0
-  %a1 = getelementptr inbounds float, float* %p, i32 1
-  store float 0.000000e+00, float* %a0
-  store float 0.000000e+00, float* %a1
-  %zero = load float, float* %a0
-  %fmul1 = fmul fast float %zero, %src
-  %fadd1 = fadd fast float %fmul1, %zero
-  %fmul2 = fmul fast float %fadd1, 2.000000e+00
-  %fmul3 = fmul fast float %fmul2, %fmul2
-  %fmul4 = fmul fast float %fmul2, 2.000000e+00
-  %fadd2 = fadd fast float %fmul4, -3.000000e+00
-  %fmul5 = fmul fast float %fadd2, %fmul2
-  %fadd3 = fadd fast float %fmul2, %src
-  %fadd4 = fadd fast float %fadd3, %fmul5
-  %fmul6 = fmul fast float %fmul3, %fadd4
-  ret float %fmul6
-}