[TableGen] Fix a potential crash when operand doesn't appear in the instruction pattern

[shiltian]

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.

[llvmbot]

@llvm/pr-subscribers-backend-amdgpu

Author: Shilei Tian (shiltian)

Changes

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 causes crash. This is a very
trivial fix.

---

Full diff: https://github.com/llvm/llvm-project/pull/87663.diff

2 Files Affected:

• (modified) llvm/lib/Target/AMDGPU/VOP3PInstructions.td (+2-2)
• (modified) llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp (+1)

diff --git a/llvm/lib/Target/AMDGPU/VOP3PInstructions.td b/llvm/lib/Target/AMDGPU/VOP3PInstructions.td
index a7d63fdb2e04c8..c929506601c067 100644
--- a/llvm/lib/Target/AMDGPU/VOP3PInstructions.td
+++ b/llvm/lib/Target/AMDGPU/VOP3PInstructions.td
@@ -564,9 +564,9 @@ class VOPProfileSMFMAC<VOPProfile P, RegisterOperand _DstRC,
   : VOPProfileMAI<P, _DstRC, _DstRC, _SrcARC> {
   let Src1RC64 = _SrcBRC;
   let Src2VT = DstVT;
-  let Asm64 = " $vdst, $src0, $src1, $idx$cbsz$abid";
+  let Asm64 = " $vdst, $src0, $src1, $idx$cbsz$abid$clamp";
   let Outs64 = (outs DstRC:$vdst);
-  let Ins64 = (ins Src0RC64:$src0, Src1RC64:$src1, VRegSrc_32:$idx, CBSZ:$cbsz, ABID:$abid, Src2RC64:$src2);
+  let Ins64 = (ins Src0RC64:$src0, Src1RC64:$src1, VRegSrc_32:$idx, CBSZ:$cbsz, ABID:$abid, clampmod:$clamp, Src2RC64:$src2);
 }
 
 def VOPProfileMAI_F32_F32_X4    : VOPProfileMAI<VOP_V4F32_F32_F32_V4F32,       AISrc_128_f32,  ADst_128>;
diff --git a/llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp b/llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp
index 076d0427a85971..eeb3d6873e9915 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");
+      return;
     }
     TreePatternNodePtr InVal = InstInputs[OpName];
     InstInputs.erase(OpName); // It occurred, remove from map.

[kosarev]

LGTM.