[llvm] [RISCV] Check dead flag on VL def op in RISCVCoalesceVSETVLI. NFC (PR #91168)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

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

Author: Luke Lau (lukel97)

<details>
<summary>Changes</summary>

Because LiveVariables has been run, we no longer need to lookup the users in MachineRegisterInfo anymore and can instead just check for the dead flag.


---
Full diff: https://github.com/llvm/llvm-project/pull/91168.diff


1 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp (+1-3) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp b/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
index 216dc78085204e..eaebdc2e54bef4 100644
--- a/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
+++ b/llvm/lib/Target/RISCV/RISCVInsertVSETVLI.cpp
@@ -1600,9 +1600,7 @@ bool RISCVCoalesceVSETVLI::coalesceVSETVLIs(MachineBasicBlock &MBB) {
       continue;
     }
 
-    Register RegDef = MI.getOperand(0).getReg();
-    assert(RegDef == RISCV::X0 || RegDef.isVirtual());
-    if (RegDef != RISCV::X0 && !MRI->use_nodbg_empty(RegDef))
+    if (!MI.getOperand(0).isDead())
       Used.demandVL();
 
     if (NextMI) {

``````````

</details>


https://github.com/llvm/llvm-project/pull/91168