[llvm] [RISCV] RISCVISD::SELECT_CC is for integer comparisons only which can't create poison (PR #151943)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon created https://github.com/llvm/llvm-project/pull/151943

The result type is irrelevant - its the comparison type that matters

>From 321d423775b78539481e8c68edfd083d3c1d63e7 Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev at redking.me.uk>
Date: Mon, 4 Aug 2025 12:14:29 +0100
Subject: [PATCH] [RISCV] RISCVISD::SELECT_CC is for integer comparisons only
 which can't create poison

The result type is irrelevant - its the comparison type that matters
---
 llvm/lib/Target/RISCV/RISCVISelLowering.cpp | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
index b6d1ee8bc3050..9e1deea93b971 100644
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -21478,11 +21478,10 @@ bool RISCVTargetLowering::canCreateUndefOrPoisonForTargetNode(
   // TODO: Add more target nodes.
   switch (Op.getOpcode()) {
   case RISCVISD::SELECT_CC:
-    // Integer select_cc cannot create poison.
-    // TODO: What are the FP poison semantics?
-    // TODO: This instruction blocks poison from the unselected operand, can
-    // we do anything with that?
-    return !Op.getValueType().isInteger();
+    // Integer comparisons cannot create poison.
+    assert(Op.getOperand(0).getValueType().isInteger() &&
+           "RISCVISD::SELECT_CC only compares integers");
+    return false;
   }
   return TargetLowering::canCreateUndefOrPoisonForTargetNode(
       Op, DemandedElts, DAG, PoisonOnly, ConsiderFlags, Depth);