[Mlir-commits] [mlir] [mlir][SPIRVToLLVM] Erase empty `spirv.mlir.loop` in `LoopPattern` (PR #113527)

[llvmlistbot at llvm.org]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-mlir-spirv

Author: Longsheng Mou (CoTinker)

<details>
<summary>Changes</summary>

This PR erases `spirv.mlir.loop` with an empty region in `LoopPattern`, resolving a crash. Fixes #<!-- -->113404.

---
Full diff: https://github.com/llvm/llvm-project/pull/113527.diff


2 Files Affected:

- (modified) mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp (+6) 
- (modified) mlir/test/Conversion/SPIRVToLLVM/control-flow-ops-to-llvm.mlir (+8) 


``````````diff
diff --git a/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp b/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
index 74c169c9a7e76a..044a3c8c65e3b2 100644
--- a/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
+++ b/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
@@ -1083,6 +1083,12 @@ class LoopPattern : public SPIRVToLLVMConversion<spirv::LoopOp> {
     if (loopOp.getLoopControl() != spirv::LoopControl::None)
       return failure();
 
+    // `spirv.mlir.loop` with empty region is redundant and should be erased.
+    if (loopOp.getBody().empty()) {
+      rewriter.eraseOp(loopOp);
+      return success();
+    }
+
     Location loc = loopOp.getLoc();
 
     // Split the current block after `spirv.mlir.loop`. The remaining ops will
diff --git a/mlir/test/Conversion/SPIRVToLLVM/control-flow-ops-to-llvm.mlir b/mlir/test/Conversion/SPIRVToLLVM/control-flow-ops-to-llvm.mlir
index 3557830e779e24..756fc5415e20f7 100644
--- a/mlir/test/Conversion/SPIRVToLLVM/control-flow-ops-to-llvm.mlir
+++ b/mlir/test/Conversion/SPIRVToLLVM/control-flow-ops-to-llvm.mlir
@@ -86,6 +86,14 @@ spirv.module Logical GLSL450 {
 //===----------------------------------------------------------------------===//
 
 spirv.module Logical GLSL450 {
+  // CHECK-LABEL: @empty_loop
+  spirv.func @empty_loop() "None" {
+    // CHECK: llvm.return
+    spirv.mlir.loop {
+    }
+    spirv.Return
+  }
+
   // CHECK-LABEL: @infinite_loop
   spirv.func @infinite_loop(%count : i32) -> () "None" {
     // CHECK:   llvm.br ^[[BB1:.*]]

``````````

</details>


https://github.com/llvm/llvm-project/pull/113527