[SPIR-V] Move structurizer to ISel prepare

[Keenuts]

Some passes like LoopSimplify/SimplifyCFF are running between IRPasses and ISelPrepare. This is an issue because the structurizer generates OpSelectionMerge/OpLoopMerge instructions at specific places, and those passes are moving them.
Moving the structurizer later solves this issue.

[llvmbot]

@llvm/pr-subscribers-backend-spir-v

Author: Nathan Gauër (Keenuts)

Changes

Some passes like LoopSimplify/SimplifyCFF are running between IRPasses and ISelPrepare. This is an issue because the structurizer generates OpSelectionMerge/OpLoopMerge instructions at specific places, and those passes are moving them.
Moving the structurizer later solves this issue.

---

Full diff: https://github.com/llvm/llvm-project/pull/157886.diff

1 Files Affected:

• (modified) llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp (+5-5)

diff --git a/llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp b/llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp
index e0bfb77f4b530..9c58f468c9bd6 100644
--- a/llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVTargetMachine.cpp
@@ -189,6 +189,11 @@ TargetPassConfig *SPIRVTargetMachine::createPassConfig(PassManagerBase &PM) {
 void SPIRVPassConfig::addIRPasses() {
   TargetPassConfig::addIRPasses();
 
+  addPass(createSPIRVRegularizerPass());
+  addPass(createSPIRVPrepareFunctionsPass(TM));
+}
+
+void SPIRVPassConfig::addISelPrepare() {
   if (TM.getSubtargetImpl()->isShader()) {
     // Vulkan does not allow address space casts. This pass is run to remove
     // address space casts that can be removed.
@@ -220,12 +225,7 @@ void SPIRVPassConfig::addIRPasses() {
     addPass(createPromoteMemoryToRegisterPass());
   }
 
-  addPass(createSPIRVRegularizerPass());
-  addPass(createSPIRVPrepareFunctionsPass(TM));
   addPass(createSPIRVStripConvergenceIntrinsicsPass());
-}
-
-void SPIRVPassConfig::addISelPrepare() {
   addPass(createSPIRVLegalizeImplicitBindingPass());
   addPass(createSPIRVEmitIntrinsicsPass(&getTM<SPIRVTargetMachine>()));
   if (TM.getSubtargetImpl()->isLogicalSPIRV())

[Keenuts]

Rebased on main. There was one SPIR-V test failure I could not reproduce locally. Will see if this has been fixed, or if I need to dig into it first.

[Keenuts]

Turns out my version of spirv-val was just too old. Can reproduce the issue which is also on main, so unrelated to this PR.