[llvm] [WebAssembly] Use RefTypeMem2Local instead of Mem2Reg (PR #83196)
Heejin Ahn via llvm-commits
llvm-commits at lists.llvm.org
Tue Feb 27 14:11:22 PST 2024
https://github.com/aheejin created https://github.com/llvm/llvm-project/pull/83196
When reference-types feature is enabled, forcing mem2reg unconditionally even in `-O0` has some problems described in #81575. This uses RefTypeMem2Local pass added in #81965 instead. This also removes `IsForced` parameter added in
https://github.com/llvm/llvm-project/commit/890146b19206827bc48ee1ae1dc1534ff2ff18d7 given that we don't need it anymore.
This may still hurt debug info related to reference type variables a little during the backend transformation given that they are not stored in memory anymore, but reference type variables are presumably rare and it would be still a lot less damage than forcing mem2reg on the whole program. Also this fixes the EH problem described in #81575.
Fixes #81575.
cc @xortoast
>From a13de6169de830491c7dabd2fe6b4852efd28971 Mon Sep 17 00:00:00 2001
From: Heejin Ahn <aheejin at gmail.com>
Date: Fri, 16 Feb 2024 21:21:44 +0000
Subject: [PATCH] [WebAssembly] Use RefTypeMem2Local instead of Mem2Reg
When reference-types feature is enabled, forcing mem2reg unconditionally
even in `-O0` has some problems described in #81575. This uses
RefTypeMem2Local pass added in #81965 instead. This also removes
`IsForced` parameter added in
https://github.com/llvm/llvm-project/commit/890146b19206827bc48ee1ae1dc1534ff2ff18d7
given that we don't need it anymore.
This may still hurt debug info related to reference type variables a
little during the backend transformation given that they are not stored
in memory anymore, but reference type variables are presumably rare and
it would be still a lot less damage than forcing mem2reg on the whole
program. Also this fixes the EH problem described in #81575.
Fixes #81575.
---
llvm/include/llvm/Transforms/Utils.h | 2 +-
.../Target/WebAssembly/WebAssemblyTargetMachine.cpp | 5 +++--
llvm/lib/Transforms/Utils/Mem2Reg.cpp | 12 ++++--------
llvm/test/CodeGen/WebAssembly/ref-type-mem2local.ll | 1 +
4 files changed, 9 insertions(+), 11 deletions(-)
diff --git a/llvm/include/llvm/Transforms/Utils.h b/llvm/include/llvm/Transforms/Utils.h
index 0fa6de3f67130a..c6a6a05f3fddb4 100644
--- a/llvm/include/llvm/Transforms/Utils.h
+++ b/llvm/include/llvm/Transforms/Utils.h
@@ -70,7 +70,7 @@ extern char &LCSSAID;
// %Y = load i32* %X
// ret i32 %Y
//
-FunctionPass *createPromoteMemoryToRegisterPass(bool IsForced = false);
+FunctionPass *createPromoteMemoryToRegisterPass();
//===----------------------------------------------------------------------===//
//
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index d088c7d925ddf0..cb6e9eef365dd4 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -487,8 +487,9 @@ void WebAssemblyPassConfig::addISelPrepare() {
WasmTM->getSubtargetImpl(std::string(WasmTM->getTargetCPU()),
std::string(WasmTM->getTargetFeatureString()));
if (Subtarget->hasReferenceTypes()) {
- // We need to remove allocas for reference types
- addPass(createPromoteMemoryToRegisterPass(true));
+ // We need to move reference type allocas to WASM_ADDRESS_SPACE_VAR so that
+ // loads and stores are promoted to local.gets/local.sets.
+ addPass(createWebAssemblyRefTypeMem2Local());
}
// Lower atomics and TLS if necessary
addPass(new CoalesceFeaturesAndStripAtomics(&getWebAssemblyTargetMachine()));
diff --git a/llvm/lib/Transforms/Utils/Mem2Reg.cpp b/llvm/lib/Transforms/Utils/Mem2Reg.cpp
index fbc6dd7613deb8..5ad7aeb463ecb2 100644
--- a/llvm/lib/Transforms/Utils/Mem2Reg.cpp
+++ b/llvm/lib/Transforms/Utils/Mem2Reg.cpp
@@ -74,19 +74,15 @@ namespace {
struct PromoteLegacyPass : public FunctionPass {
// Pass identification, replacement for typeid
static char ID;
- bool ForcePass; /// If true, forces pass to execute, instead of skipping.
- PromoteLegacyPass() : FunctionPass(ID), ForcePass(false) {
- initializePromoteLegacyPassPass(*PassRegistry::getPassRegistry());
- }
- PromoteLegacyPass(bool IsForced) : FunctionPass(ID), ForcePass(IsForced) {
+ PromoteLegacyPass() : FunctionPass(ID) {
initializePromoteLegacyPassPass(*PassRegistry::getPassRegistry());
}
// runOnFunction - To run this pass, first we calculate the alloca
// instructions that are safe for promotion, then we promote each one.
bool runOnFunction(Function &F) override {
- if (!ForcePass && skipFunction(F))
+ if (skipFunction(F))
return false;
DominatorTree &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
@@ -115,6 +111,6 @@ INITIALIZE_PASS_END(PromoteLegacyPass, "mem2reg", "Promote Memory to Register",
false, false)
// createPromoteMemoryToRegister - Provide an entry point to create this pass.
-FunctionPass *llvm::createPromoteMemoryToRegisterPass(bool IsForced) {
- return new PromoteLegacyPass(IsForced);
+FunctionPass *llvm::createPromoteMemoryToRegisterPass() {
+ return new PromoteLegacyPass();
}
diff --git a/llvm/test/CodeGen/WebAssembly/ref-type-mem2local.ll b/llvm/test/CodeGen/WebAssembly/ref-type-mem2local.ll
index a38243ca218cc1..31d37db5318930 100644
--- a/llvm/test/CodeGen/WebAssembly/ref-type-mem2local.ll
+++ b/llvm/test/CodeGen/WebAssembly/ref-type-mem2local.ll
@@ -1,4 +1,5 @@
; RUN: opt < %s -wasm-ref-type-mem2local -S | FileCheck %s
+; RUN: llc < %s -mattr=+reference-types -stop-after=wasm-ref-type-mem2local | FileCheck %s
target triple = "wasm32-unknown-unknown"
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