[llvm] 3e1d2c3 - [InstCombine] Fix or of commuted foldable predicates

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2022-04-22T12:31:26+02:00
New Revision: 3e1d2c352c1fb9fb7022344fb4e5639b4f5b1c45

URL: https://github.com/llvm/llvm-project/commit/3e1d2c352c1fb9fb7022344fb4e5639b4f5b1c45
DIFF: https://github.com/llvm/llvm-project/commit/3e1d2c352c1fb9fb7022344fb4e5639b4f5b1c45.diff

LOG: [InstCombine] Fix or of commuted foldable predicates

1d90e530442477de247dcb613f5176fe7e9beded switch this code to store
the predicates and operands in variables, but retained a
swapOperands() call here. Thus the commuted cases were no longer
folded. Additionally, as the change was not reported, the next
InstCombine iteration would not pick it up either.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/test/Transforms/InstCombine/or.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index b8dba03e5e689..d596033ec22c2 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2580,11 +2580,12 @@ Value *InstCombinerImpl::foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
 
   // (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
   if (predicatesFoldable(PredL, PredR)) {
-    if (LHS0 == RHS1 && LHS1 == RHS0)
-      LHS->swapOperands();
+    if (LHS0 == RHS1 && LHS1 == RHS0) {
+      PredL = ICmpInst::getSwappedPredicate(PredL);
+      std::swap(LHS0, LHS1);
+    }
     if (LHS0 == RHS0 && LHS1 == RHS1) {
-      unsigned Code =
-          getICmpCode(LHS->getPredicate()) | getICmpCode(RHS->getPredicate());
+      unsigned Code = getICmpCode(PredL) | getICmpCode(PredR);
       bool IsSigned = LHS->isSigned() || RHS->isSigned();
       return getNewICmpValue(Code, IsSigned, LHS0, LHS1, Builder);
     }

diff  --git a/llvm/test/Transforms/InstCombine/or.ll b/llvm/test/Transforms/InstCombine/or.ll
index 09d6780c917d8..b1ff6830a3783 100644
--- a/llvm/test/Transforms/InstCombine/or.ll
+++ b/llvm/test/Transforms/InstCombine/or.ll
@@ -39,10 +39,8 @@ define i1 @test14(i32 %A, i32 %B) {
 
 define i1 @test14_commuted(i32 %A, i32 %B) {
 ; CHECK-LABEL: @test14_commuted(
-; CHECK-NEXT:    [[C1:%.*]] = icmp ugt i32 [[B:%.*]], [[A:%.*]]
-; CHECK-NEXT:    [[C2:%.*]] = icmp ult i32 [[B]], [[A]]
-; CHECK-NEXT:    [[D:%.*]] = or i1 [[C1]], [[C2]]
-; CHECK-NEXT:    ret i1 [[D]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp ne i32 [[B:%.*]], [[A:%.*]]
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ;
   %C1 = icmp ult i32 %A, %B
   %C2 = icmp ult i32 %B, %A