[llvm] [RISCV] Check vmerge's true is in same block in vmerge -> vmv.v.v peephole (PR #110861)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Luke Lau (lukel97)

<details>
<summary>Changes</summary>

The peepholes in RISCVVectorPeephole need to be local and we were failing to check if the true operand was in the same block as the vmerge.

Fixes #<!-- -->110832


---
Full diff: https://github.com/llvm/llvm-project/pull/110861.diff


2 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp (+2-2) 
- (modified) llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-to-vmv.mir (+26) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp b/llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp
index 026e5d653c38c2..b883c50beadc09 100644
--- a/llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp
+++ b/llvm/lib/Target/RISCV/RISCVVectorPeephole.cpp
@@ -419,8 +419,8 @@ bool RISCVVectorPeephole::convertSameMaskVMergeToVMv(MachineInstr &MI) {
   if (!NewOpc)
     return false;
   MachineInstr *True = MRI->getVRegDef(MI.getOperand(3).getReg());
-  if (!True || !RISCV::getMaskedPseudoInfo(True->getOpcode()) ||
-      !hasSameEEW(MI, *True))
+  if (!True || True->getParent() != MI.getParent() ||
+      !RISCV::getMaskedPseudoInfo(True->getOpcode()) || !hasSameEEW(MI, *True))
     return false;
 
   const MachineInstr *TrueV0Def = V0Defs.lookup(True);
diff --git a/llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-to-vmv.mir b/llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-to-vmv.mir
index e2f1fe4094b5c9..a5622fd466217c 100644
--- a/llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-to-vmv.mir
+++ b/llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-to-vmv.mir
@@ -159,3 +159,29 @@ body: |
     $v0 = COPY %mask
     %x:vrnov0 = PseudoVMERGE_VVM_M1 $noreg, %false, %true, $v0, 4, 5 /* e32 */
 ...
+---
+# Shouldn't be converted because true is in a different block
+name: same_mask_diff_blocks
+body: |
+  ; CHECK-LABEL: name: same_mask_diff_blocks
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   successors: %bb.1(0x80000000)
+  ; CHECK-NEXT:   liveins: $v8, $v0
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   %false:vr = COPY $v8
+  ; CHECK-NEXT:   %mask:vr = COPY $v0
+  ; CHECK-NEXT:   $v0 = COPY %mask
+  ; CHECK-NEXT:   %true:vrnov0 = PseudoVADD_VV_M1_MASK $noreg, $noreg, $noreg, $v0, 4, 5 /* e32 */, 0 /* tu, mu */
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   $v0 = COPY %mask
+  ; CHECK-NEXT:   [[PseudoVMERGE_VVM_M1_:%[0-9]+]]:vrnov0 = PseudoVMERGE_VVM_M1 $noreg, %false, %true, $v0, 4, 5 /* e32 */
+  bb.0:
+    liveins: $v8, $v0
+    %false:vr = COPY $v8
+    %mask:vr = COPY $v0
+    $v0 = COPY %mask
+    %true:vrnov0 = PseudoVADD_VV_M1_MASK $noreg, $noreg, $noreg, $v0, 4, 5 /* e32 */, 0 /* tu, mu */
+  bb.1:
+    $v0 = COPY %mask
+    %5:vrnov0 = PseudoVMERGE_VVM_M1 $noreg, %false, %true, $v0, 4, 5 /* e32 */

``````````

</details>


https://github.com/llvm/llvm-project/pull/110861