[clang] [clang][x86] Ensure we use the shifted value bit width to check for out of bounds per-element shift amounts (PR #156019)

[Simon Pilgrim via cfe-commits]

https://github.com/RKSimon created https://github.com/llvm/llvm-project/pull/156019

This should allow us to reuse these cases for the shift-by-immediate builtins in #155542

>From a039f7803c00069517084455491d18f53659e0c2 Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev at redking.me.uk>
Date: Fri, 29 Aug 2025 14:00:12 +0100
Subject: [PATCH] [clang][x86] Ensure we use the shifted value bit width to
 check for out of bounds per-element shift amounts

This should allow us to reuse these cases for the shift-by-immediate builtins in #155542
---
 clang/lib/AST/ByteCode/InterpBuiltin.cpp | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index eba0b25997699..3bfe54e00a049 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -3256,8 +3256,8 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
   case clang::X86::BI__builtin_ia32_psllv8si:
     return interp__builtin_elementwise_int_binop(
         S, OpPC, Call, BuiltinID, [](const APSInt &LHS, const APSInt &RHS) {
-          if (RHS.uge(RHS.getBitWidth())) {
-            return APInt::getZero(RHS.getBitWidth());
+          if (RHS.uge(LHS.getBitWidth())) {
+            return APInt::getZero(LHS.getBitWidth());
           }
           return LHS.shl(RHS.getZExtValue());
         });
@@ -3266,8 +3266,8 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
   case clang::X86::BI__builtin_ia32_psrav8si:
     return interp__builtin_elementwise_int_binop(
         S, OpPC, Call, BuiltinID, [](const APSInt &LHS, const APSInt &RHS) {
-          if (RHS.uge(RHS.getBitWidth())) {
-            return LHS.ashr(RHS.getBitWidth() - 1);
+          if (RHS.uge(LHS.getBitWidth())) {
+            return LHS.ashr(LHS.getBitWidth() - 1);
           }
           return LHS.ashr(RHS.getZExtValue());
         });
@@ -3278,8 +3278,8 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
   case clang::X86::BI__builtin_ia32_psrlv8si:
     return interp__builtin_elementwise_int_binop(
         S, OpPC, Call, BuiltinID, [](const APSInt &LHS, const APSInt &RHS) {
-          if (RHS.uge(RHS.getBitWidth())) {
-            return APInt::getZero(RHS.getBitWidth());
+          if (RHS.uge(LHS.getBitWidth())) {
+            return APInt::getZero(LHS.getBitWidth());
           }
           return LHS.lshr(RHS.getZExtValue());
         });