[llvm] [WebAssembly] Support MIR printing of reference types (PR #113028)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-webassembly

Author: Heejin Ahn (aheejin)

<details>
<summary>Changes</summary>

When printing a memory operand in MIR, this line
https://github.com/llvm/llvm-project/blob/d37bc32a65651e647148236ffb9728ea2e77eac3/llvm/lib/CodeGen/MachineOperand.cpp#L1247 calls this
https://github.com/llvm/llvm-project/blob/d37bc32a65651e647148236ffb9728ea2e77eac3/llvm/include/llvm/Support/Alignment.h#L238 which assumes `Rhs` (the size in this case) is positive.

But Wasm reference types' size is set to 0:
https://github.com/llvm/llvm-project/blob/d37bc32a65651e647148236ffb9728ea2e77eac3/llvm/include/llvm/CodeGen/ValueTypes.td#L326-L328

It looks they didn't have a problem being printed in MIR until #<!-- -->84751, which somehow removed the condition of `getSize() > 0` in that line. This revives the condition so that Wasm reference types will not crash the MIR printer.

---
Full diff: https://github.com/llvm/llvm-project/pull/113028.diff


2 Files Affected:

- (modified) llvm/lib/CodeGen/MachineOperand.cpp (+2-1) 
- (modified) llvm/test/CodeGen/WebAssembly/externref-globalget.ll (+3) 


``````````diff
diff --git a/llvm/lib/CodeGen/MachineOperand.cpp b/llvm/lib/CodeGen/MachineOperand.cpp
index 89d32c3f005e00..c0e004555de959 100644
--- a/llvm/lib/CodeGen/MachineOperand.cpp
+++ b/llvm/lib/CodeGen/MachineOperand.cpp
@@ -1244,7 +1244,8 @@ void MachineMemOperand::print(raw_ostream &OS, ModuleSlotTracker &MST,
   }
   MachineOperand::printOperandOffset(OS, getOffset());
   if (!getSize().hasValue() ||
-      getAlign() != getSize().getValue().getKnownMinValue())
+      (!getSize().isZero() &&
+       getAlign() != getSize().getValue().getKnownMinValue()))
     OS << ", align " << getAlign().value();
   if (getAlign() != getBaseAlign())
     OS << ", basealign " << getBaseAlign().value();
diff --git a/llvm/test/CodeGen/WebAssembly/externref-globalget.ll b/llvm/test/CodeGen/WebAssembly/externref-globalget.ll
index cdf98c42439f2d..79d7932486e226 100644
--- a/llvm/test/CodeGen/WebAssembly/externref-globalget.ll
+++ b/llvm/test/CodeGen/WebAssembly/externref-globalget.ll
@@ -1,4 +1,7 @@
 ; RUN: llc < %s --mtriple=wasm32-unknown-unknown -asm-verbose=false -mattr=+reference-types | FileCheck %s
+; Test for MIR printing of reference types in other address spaces. This should
+; not error out.
+; RUN: llc < %s --mtriple=wasm32-unknown-unknown -asm-verbose=false -mattr=+reference-types -print-after=finalize-isel | FileCheck %s
 
 %externref = type ptr addrspace(10) ;; addrspace 10 is nonintegral
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/113028