[llvm] [TableGen] Fix a potential crash when operand doesn't appear in the instruction pattern (PR #87663)

[Shilei Tian via llvm-commits]

https://github.com/shiltian updated https://github.com/llvm/llvm-project/pull/87663

>From 85ff6d6a297067e0058c96b5b411acfc2886ac6a Mon Sep 17 00:00:00 2001
From: Shilei Tian <i at tianshilei.me>
Date: Thu, 4 Apr 2024 15:54:45 -0400
Subject: [PATCH] [TableGen] Fix a potential crash when operand doesn't appear
 in the instruction pattern

We have a check of whether an operand is in the instruction pattern, and emit an
error if it is not, but we simply continue execution, including directly
dereferencing a point-like object `InVal`, which will be just created when
accessing the map. It contains a `nullptr` so dereferencing it causes crash.
This is a very trivial fix.
---
 llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp b/llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp
index 076d0427a85971..61402615d9316c 100644
--- a/llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp
+++ b/llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp
@@ -3872,6 +3872,7 @@ void CodeGenDAGPatterns::parseInstructionPattern(CodeGenInstruction &CGI,
       }
       I.error("Operand $" + OpName +
               " does not appear in the instruction pattern");
+      continue;
     }
     TreePatternNodePtr InVal = InstInputs[OpName];
     InstInputs.erase(OpName); // It occurred, remove from map.