[llvm] r352681 - [WebAssembly] Restore stack pointer right after catch instruction
Heejin Ahn via llvm-commits
llvm-commits at lists.llvm.org
Wed Jan 30 14:44:45 PST 2019
Author: aheejin
Date: Wed Jan 30 14:44:45 2019
New Revision: 352681
URL: http://llvm.org/viewvc/llvm-project?rev=352681&view=rev
Log:
[WebAssembly] Restore stack pointer right after catch instruction
Summary:
After the staack is unwound due to a thrown exxception,
`__stack_pointer` global can point to an invalid address. So
a `global.set` to restore `__stack_pointer` should be inserted right
after `catch` instruction.
But after r352598 the `global.set` instruction is inserted not right
after `catch` but after `block` - `br-on-exn` - `end_block` -
`extract_exception` sequence. This CL fixes it.
While doing that, we can actually move ReplacePhysRegs pass after
LateEHPrepare and merge EHRestoreStackPointer pass into LateEHPrepare,
and now placing `global.set` to `__stack_pointer` right after `catch` is
much easier. Otherwise it is hard to guarantee that `global.set` is
still right after `catch` and not touched with other transformations, in
which case we have to do something to hoist it.
Reviewers: dschuff
Subscribers: mgorny, sbc100, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D57421
Removed:
llvm/trunk/lib/Target/WebAssembly/WebAssemblyEHRestoreStackPointer.cpp
Modified:
llvm/trunk/lib/Target/WebAssembly/CMakeLists.txt
llvm/trunk/lib/Target/WebAssembly/WebAssembly.h
llvm/trunk/lib/Target/WebAssembly/WebAssemblyLateEHPrepare.cpp
llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
llvm/trunk/test/CodeGen/WebAssembly/exception.ll
Modified: llvm/trunk/lib/Target/WebAssembly/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/CMakeLists.txt?rev=352681&r1=352680&r2=352681&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/CMakeLists.txt (original)
+++ llvm/trunk/lib/Target/WebAssembly/CMakeLists.txt Wed Jan 30 14:44:45 2019
@@ -21,7 +21,6 @@ add_llvm_target(WebAssemblyCodeGen
WebAssemblyCFGSort.cpp
WebAssemblyDebugValueManager.cpp
WebAssemblyLateEHPrepare.cpp
- WebAssemblyEHRestoreStackPointer.cpp
WebAssemblyExceptionInfo.cpp
WebAssemblyExplicitLocals.cpp
WebAssemblyFastISel.cpp
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssembly.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssembly.h?rev=352681&r1=352680&r2=352681&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssembly.h (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssembly.h Wed Jan 30 14:44:45 2019
@@ -38,7 +38,6 @@ FunctionPass *createWebAssemblyArgumentM
FunctionPass *createWebAssemblySetP2AlignOperands();
// Late passes.
-FunctionPass *createWebAssemblyEHRestoreStackPointer();
FunctionPass *createWebAssemblyReplacePhysRegs();
FunctionPass *createWebAssemblyPrepareForLiveIntervals();
FunctionPass *createWebAssemblyOptimizeLiveIntervals();
@@ -63,7 +62,6 @@ void initializeFixFunctionBitcastsPass(P
void initializeOptimizeReturnedPass(PassRegistry &);
void initializeWebAssemblyArgumentMovePass(PassRegistry &);
void initializeWebAssemblySetP2AlignOperandsPass(PassRegistry &);
-void initializeWebAssemblyEHRestoreStackPointerPass(PassRegistry &);
void initializeWebAssemblyReplacePhysRegsPass(PassRegistry &);
void initializeWebAssemblyPrepareForLiveIntervalsPass(PassRegistry &);
void initializeWebAssemblyOptimizeLiveIntervalsPass(PassRegistry &);
Removed: llvm/trunk/lib/Target/WebAssembly/WebAssemblyEHRestoreStackPointer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyEHRestoreStackPointer.cpp?rev=352680&view=auto
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyEHRestoreStackPointer.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyEHRestoreStackPointer.cpp (removed)
@@ -1,86 +0,0 @@
-//===-- WebAssemblyEHRestoreStackPointer.cpp - __stack_pointer restoration ===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-///
-/// \file
-/// After the stack is unwound due to a thrown exception, the __stack_pointer
-/// global can point to an invalid address. This inserts instructions that
-/// restore __stack_pointer global.
-///
-//===----------------------------------------------------------------------===//
-
-#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
-#include "WebAssembly.h"
-#include "WebAssemblySubtarget.h"
-#include "WebAssemblyUtilities.h"
-#include "llvm/CodeGen/MachineFrameInfo.h"
-#include "llvm/MC/MCAsmInfo.h"
-using namespace llvm;
-
-#define DEBUG_TYPE "wasm-eh-restore-stack-pointer"
-
-namespace {
-class WebAssemblyEHRestoreStackPointer final : public MachineFunctionPass {
-public:
- static char ID; // Pass identification, replacement for typeid
- WebAssemblyEHRestoreStackPointer() : MachineFunctionPass(ID) {}
-
- StringRef getPassName() const override {
- return "WebAssembly Restore Stack Pointer for Exception Handling";
- }
-
- void getAnalysisUsage(AnalysisUsage &AU) const override {
- AU.setPreservesCFG();
- MachineFunctionPass::getAnalysisUsage(AU);
- }
-
- bool runOnMachineFunction(MachineFunction &MF) override;
-};
-} // end anonymous namespace
-
-char WebAssemblyEHRestoreStackPointer::ID = 0;
-INITIALIZE_PASS(WebAssemblyEHRestoreStackPointer, DEBUG_TYPE,
- "Restore Stack Pointer for Exception Handling", true, false)
-
-FunctionPass *llvm::createWebAssemblyEHRestoreStackPointer() {
- return new WebAssemblyEHRestoreStackPointer();
-}
-
-bool WebAssemblyEHRestoreStackPointer::runOnMachineFunction(
- MachineFunction &MF) {
- LLVM_DEBUG(dbgs() << "********** EH Restore Stack Pointer **********\n"
- "********** Function: "
- << MF.getName() << '\n');
-
- const auto *FrameLowering = static_cast<const WebAssemblyFrameLowering *>(
- MF.getSubtarget().getFrameLowering());
- if (!FrameLowering->needsPrologForEH(MF))
- return false;
- bool Changed = false;
-
- for (auto &MBB : MF) {
- if (!MBB.isEHPad())
- continue;
- Changed = true;
-
- // Insert __stack_pointer restoring instructions at the beginning of each EH
- // pad, after the catch instruction. (Catch instructions may have been
- // reordered, and catch_all instructions have not been inserted yet, but
- // those cases are handled in LateEHPrepare).
- //
- // Here it is safe to assume that SP32 holds the latest value of
- // __stack_pointer, because the only exception for this case is when a
- // function uses the red zone, but that only happens with leaf functions,
- // and we don't restore __stack_pointer in leaf functions anyway.
- auto InsertPos = MBB.begin();
- if (MBB.begin()->getOpcode() == WebAssembly::CATCH)
- InsertPos++;
- FrameLowering->writeSPToGlobal(WebAssembly::SP32, MF, MBB, InsertPos,
- MBB.begin()->getDebugLoc());
- }
- return Changed;
-}
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyLateEHPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyLateEHPrepare.cpp?rev=352681&r1=352680&r2=352681&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyLateEHPrepare.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyLateEHPrepare.cpp Wed Jan 30 14:44:45 2019
@@ -34,6 +34,7 @@ class WebAssemblyLateEHPrepare final : p
bool replaceFuncletReturns(MachineFunction &MF);
bool addCatches(MachineFunction &MF);
bool addExceptionExtraction(MachineFunction &MF);
+ bool restoreStackPointer(MachineFunction &MF);
public:
static char ID; // Pass identification, replacement for typeid
@@ -113,6 +114,7 @@ bool WebAssemblyLateEHPrepare::runOnMach
Changed |= replaceFuncletReturns(MF);
Changed |= addCatches(MF);
Changed |= addExceptionExtraction(MF);
+ Changed |= restoreStackPointer(MF);
return Changed;
}
@@ -330,3 +332,33 @@ bool WebAssemblyLateEHPrepare::addExcept
return true;
}
+
+// After the stack is unwound due to a thrown exception, the __stack_pointer
+// global can point to an invalid address. This inserts instructions that
+// restore __stack_pointer global.
+bool WebAssemblyLateEHPrepare::restoreStackPointer(MachineFunction &MF) {
+ const auto *FrameLowering = static_cast<const WebAssemblyFrameLowering *>(
+ MF.getSubtarget().getFrameLowering());
+ if (!FrameLowering->needsPrologForEH(MF))
+ return false;
+ bool Changed = false;
+
+ for (auto &MBB : MF) {
+ if (!MBB.isEHPad())
+ continue;
+ Changed = true;
+
+ // Insert __stack_pointer restoring instructions at the beginning of each EH
+ // pad, after the catch instruction. Here it is safe to assume that SP32
+ // holds the latest value of __stack_pointer, because the only exception for
+ // this case is when a function uses the red zone, but that only happens
+ // with leaf functions, and we don't restore __stack_pointer in leaf
+ // functions anyway.
+ auto InsertPos = MBB.begin();
+ if (MBB.begin()->getOpcode() == WebAssembly::CATCH)
+ InsertPos++;
+ FrameLowering->writeSPToGlobal(WebAssembly::SP32, MF, MBB, InsertPos,
+ MBB.begin()->getDebugLoc());
+ }
+ return Changed;
+}
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp?rev=352681&r1=352680&r2=352681&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp Wed Jan 30 14:44:45 2019
@@ -57,7 +57,6 @@ extern "C" void LLVMInitializeWebAssembl
initializeOptimizeReturnedPass(PR);
initializeWebAssemblyArgumentMovePass(PR);
initializeWebAssemblySetP2AlignOperandsPass(PR);
- initializeWebAssemblyEHRestoreStackPointerPass(PR);
initializeWebAssemblyReplacePhysRegsPass(PR);
initializeWebAssemblyPrepareForLiveIntervalsPass(PR);
initializeWebAssemblyOptimizeLiveIntervalsPass(PR);
@@ -284,14 +283,6 @@ void WebAssemblyPassConfig::addPostRegAl
void WebAssemblyPassConfig::addPreEmitPass() {
TargetPassConfig::addPreEmitPass();
- // Restore __stack_pointer global after an exception is thrown.
- addPass(createWebAssemblyEHRestoreStackPointer());
-
- // Now that we have a prologue and epilogue and all frame indices are
- // rewritten, eliminate SP and FP. This allows them to be stackified,
- // colored, and numbered with the rest of the registers.
- addPass(createWebAssemblyReplacePhysRegs());
-
// Rewrite pseudo call_indirect instructions as real instructions.
// This needs to run before register stackification, because we change the
// order of the arguments.
@@ -304,6 +295,11 @@ void WebAssemblyPassConfig::addPreEmitPa
// Every CFG-changing optimizations should come before this.
addPass(createWebAssemblyLateEHPrepare());
+ // Now that we have a prologue and epilogue and all frame indices are
+ // rewritten, eliminate SP and FP. This allows them to be stackified,
+ // colored, and numbered with the rest of the registers.
+ addPass(createWebAssemblyReplacePhysRegs());
+
// Preparations and optimizations related to register stackification.
if (getOptLevel() != CodeGenOpt::None) {
// LiveIntervals isn't commonly run this late. Re-establish preconditions.
Modified: llvm/trunk/test/CodeGen/WebAssembly/exception.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/exception.ll?rev=352681&r1=352680&r2=352681&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/exception.ll (original)
+++ llvm/trunk/test/CodeGen/WebAssembly/exception.ll Wed Jan 30 14:44:45 2019
@@ -30,12 +30,12 @@ define void @test_rethrow(i8* %p) {
; CHECK: try
; CHECK: call foo at FUNCTION
; CHECK: catch $[[EXCEPT_REF:[0-9]+]]=
+; CHECK: global.set __stack_pointer at GLOBAL
; CHECK: block i32
; CHECK: br_on_exn 0, __cpp_exception at EVENT, $[[EXCEPT_REF]]
; CHECK: rethrow
; CHECK: end_block
; CHECK: extract_exception $[[EXN:[0-9]+]]=
-; CHECK: global.set __stack_pointer at GLOBAL
; CHECK-DAG: i32.store __wasm_lpad_context
; CHECK-DAG: i32.store __wasm_lpad_context+4
; CHECK: i32.call $drop=, _Unwind_CallPersonality at FUNCTION, $[[EXN]]
More information about the llvm-commits
mailing list