[llvm] [TableGen] Validate the shift amount for !srl, !shl, and !sra operators. (PR #132492)

[Craig Topper via llvm-commits]

https://github.com/topperc created https://github.com/llvm/llvm-project/pull/132492

The C operator has undefined behavior for out of bounds shifts so we should check this.

>From 4277124e8acb8efed73dee9bc32a1744c807dcdf Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Fri, 21 Mar 2025 16:35:02 -0700
Subject: [PATCH] [TableGen] Validate the shift amount for !srl, !shl, and !sra
 operators.

The C operator has undefined behavior for out of bounds shifts
so we should check this.
---
 llvm/lib/TableGen/Record.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/TableGen/Record.cpp b/llvm/lib/TableGen/Record.cpp
index c5b9b670b6f42..655c4078697f3 100644
--- a/llvm/lib/TableGen/Record.cpp
+++ b/llvm/lib/TableGen/Record.cpp
@@ -1537,7 +1537,13 @@ const Init *BinOpInit::Fold(const Record *CurRec) const {
     if (LHSi && RHSi) {
       int64_t LHSv = LHSi->getValue(), RHSv = RHSi->getValue();
       int64_t Result;
-      switch (getOpcode()) {
+
+      unsigned Opc = getOpcode();
+      if ((Opc == SHL || Opc == SRA || Opc == SRL) && (RHSv < 0 || RHSv >= 64))
+        PrintFatalError(CurRec->getLoc(),
+                        "Illegal operation: out of bounds shift");
+
+      switch (Opc) {
       default: llvm_unreachable("Bad opcode!");
       case ADD: Result = LHSv + RHSv; break;
       case SUB: Result = LHSv - RHSv; break;
@@ -1556,7 +1562,7 @@ const Init *BinOpInit::Fold(const Record *CurRec) const {
       case OR:  Result = LHSv | RHSv; break;
       case XOR: Result = LHSv ^ RHSv; break;
       case SHL: Result = (uint64_t)LHSv << (uint64_t)RHSv; break;
-      case SRA: Result = LHSv >> RHSv; break;
+      case SRA: Result = LHSv >> (uint64_t)RHSv; break;
       case SRL: Result = (uint64_t)LHSv >> (uint64_t)RHSv; break;
       }
       return IntInit::get(getRecordKeeper(), Result);