[llvm] d6639f8 - [SDAG][RISCV] Avoid folding `setcc (xor C1, -1), C2, cond` into `setcc (xor C2, -1), C1, cond`

[Yingwei Zheng via llvm-commits]

Author: Yingwei Zheng
Date: 2023-08-24T04:18:17+08:00
New Revision: d6639f83a98f29275d4ae490d2962c1ec1d298a5

URL: https://github.com/llvm/llvm-project/commit/d6639f83a98f29275d4ae490d2962c1ec1d298a5
DIFF: https://github.com/llvm/llvm-project/commit/d6639f83a98f29275d4ae490d2962c1ec1d298a5.diff

LOG: [SDAG][RISCV] Avoid folding `setcc (xor C1, -1), C2, cond` into `setcc (xor C2, -1), C1, cond`

This patch fixes https://github.com/llvm/llvm-project/issues/64935.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D158654

Added: 
    llvm/test/CodeGen/RISCV/pr64935.ll

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

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 31b1b39b34e575..e9bd516fecdd94 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -5093,7 +5093,8 @@ SDValue TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
       if (isBitwiseNot(N1))
         return DAG.getSetCC(dl, VT, N1.getOperand(0), N0.getOperand(0), Cond);
 
-      if (DAG.isConstantIntBuildVectorOrConstantInt(N1)) {
+      if (DAG.isConstantIntBuildVectorOrConstantInt(N1) &&
+          !DAG.isConstantIntBuildVectorOrConstantInt(N0.getOperand(0))) {
         SDValue Not = DAG.getNOT(dl, N1, OpVT);
         return DAG.getSetCC(dl, VT, Not, N0.getOperand(0), Cond);
       }

diff  --git a/llvm/test/CodeGen/RISCV/pr64935.ll b/llvm/test/CodeGen/RISCV/pr64935.ll
new file mode 100644
index 00000000000000..60be5fa6c994e5
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/pr64935.ll
@@ -0,0 +1,17 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc -mtriple=riscv32 < %s | FileCheck %s
+
+define i1 @f() {
+; CHECK-LABEL: f:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    lui a0, 524288
+; CHECK-NEXT:    not a0, a0
+; CHECK-NEXT:    sltiu a0, a0, 2
+; CHECK-NEXT:    xori a0, a0, 1
+; CHECK-NEXT:    ret
+  %B25 = shl i64 4294967296, -9223372036854775808
+  %B13 = sub i64 -1, -9223372036854775808
+  %C8 = icmp ugt i64 %B13, %B25
+  %B5 = sub i64 0, 4294967296 ; Don't remove this instruction!
+  ret i1 %C8
+}