[llvm] r373301 - [WebAssembly] Unstackify regs after fixing unwinding mismatches
Heejin Ahn via llvm-commits
llvm-commits at lists.llvm.org
Mon Sep 30 23:21:54 PDT 2019
Author: aheejin
Date: Mon Sep 30 23:21:53 2019
New Revision: 373301
URL: http://llvm.org/viewvc/llvm-project?rev=373301&view=rev
Log:
[WebAssembly] Unstackify regs after fixing unwinding mismatches
Summary:
Fixing unwind mismatches for exception handling can result in splicing
existing BBs and moving some of instructions to new BBs. In this case
some of stackified def registers in the original BB can be used in the
split BB. For example, we have this BB and suppose %r0 is a stackified
register.
```
bb.1:
%r0 = call @foo
... use %r0 ...
```
After fixing unwind mismatches in CFGStackify, `bb.1` can be split and
some instructions can be moved to a newly created BB:
```
bb.1:
%r0 = call @foo
bb.split (new):
... use %r0 ...
```
In this case we should make %r0 un-stackified, because its use is now in
another BB.
When spliting a BB, this CL unstackifies all def registers that have
uses in the new split BB.
Reviewers: dschuff
Subscribers: sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D68218
Modified:
llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
llvm/trunk/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify-eh.ll
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp?rev=373301&r1=373300&r2=373301&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp Mon Sep 30 23:21:53 2019
@@ -694,8 +694,26 @@ void WebAssemblyCFGStackify::removeUnnec
}
}
+// When MBB is split into MBB and Split, we should unstackify defs in MBB that
+// have their uses in Split.
+static void unstackifyVRegsUsedInSplitBB(MachineBasicBlock &MBB,
+ MachineBasicBlock &Split,
+ WebAssemblyFunctionInfo &MFI,
+ MachineRegisterInfo &MRI) {
+ for (auto &MI : Split) {
+ for (auto &MO : MI.explicit_uses()) {
+ if (!MO.isReg() || Register::isPhysicalRegister(MO.getReg()))
+ continue;
+ if (MachineInstr *Def = MRI.getUniqueVRegDef(MO.getReg()))
+ if (Def->getParent() == &MBB)
+ MFI.unstackifyVReg(MO.getReg());
+ }
+ }
+}
+
bool WebAssemblyCFGStackify::fixUnwindMismatches(MachineFunction &MF) {
const auto &TII = *MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
+ auto &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
MachineRegisterInfo &MRI = MF.getRegInfo();
// Linearizing the control flow by placing TRY / END_TRY markers can create
@@ -1007,6 +1025,7 @@ bool WebAssemblyCFGStackify::fixUnwindMi
BrDest->insert(BrDest->end(), EndTry->removeFromParent());
// Take out the handler body from EH pad to the new branch destination BB.
BrDest->splice(BrDest->end(), EHPad, SplitPos, EHPad->end());
+ unstackifyVRegsUsedInSplitBB(*EHPad, *BrDest, MFI, MRI);
// Fix predecessor-successor relationship.
BrDest->transferSuccessors(EHPad);
EHPad->addSuccessor(BrDest);
@@ -1122,6 +1141,7 @@ bool WebAssemblyCFGStackify::fixUnwindMi
// new nested continuation BB.
NestedCont->splice(NestedCont->end(), MBB,
std::next(RangeEnd->getIterator()), MBB->end());
+ unstackifyVRegsUsedInSplitBB(*MBB, *NestedCont, MFI, MRI);
registerTryScope(NestedTry, NestedEndTry, NestedEHPad);
// Fix predecessor-successor relationship.
Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h?rev=373301&r1=373300&r2=373301&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h Mon Sep 30 23:21:53 2019
@@ -101,6 +101,11 @@ public:
VRegStackified.resize(I + 1);
VRegStackified.set(I);
}
+ void unstackifyVReg(unsigned VReg) {
+ auto I = Register::virtReg2Index(VReg);
+ if (I < VRegStackified.size())
+ VRegStackified.reset(I);
+ }
bool isVRegStackified(unsigned VReg) const {
auto I = Register::virtReg2Index(VReg);
if (I >= VRegStackified.size())
Modified: llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify-eh.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify-eh.ll?rev=373301&r1=373300&r2=373301&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify-eh.ll (original)
+++ llvm/trunk/test/CodeGen/WebAssembly/cfg-stackify-eh.ll Mon Sep 30 23:21:53 2019
@@ -436,13 +436,17 @@ try.cont:
; the right destination (label4), from which we rethrow the exception to the
; caller.
+; And the return value of 'baz' should NOT be stackified because the BB is split
+; during fixing unwind mismatches.
+
; NOSORT-LABEL: test6
; NOSORT: try
; NOSORT: call foo
; --- Nested try/catch/end_try starts
; NOSORT: try
; NOSORT: call bar
-; NOSORT: call bar
+; NOSORT: i32.call ${{[0-9]+}}=, baz
+; NOSORT-NOT: i32.call $push{{.*}}=, baz
; NOSORT: catch $[[REG:[0-9]+]]=
; NOSORT: br 1 # 1: down to label35
; NOSORT: end_try
@@ -460,7 +464,8 @@ bb0:
bb1: ; preds = %bb0
call void @bar()
- call void @bar()
+ %call = call i32 @baz()
+ call void @nothrow(i32 %call) #0
ret void
catch.dispatch0: ; preds = %bb0
@@ -618,6 +623,9 @@ try.cont:
declare void @foo()
declare void @bar()
+declare i32 @baz()
+; Function Attrs: nounwind
+declare void @nothrow(i32) #0
declare i32 @__gxx_wasm_personality_v0(...)
declare i8* @llvm.wasm.get.exception(token)
declare i32 @llvm.wasm.get.ehselector(token)
@@ -627,3 +635,5 @@ declare i8* @__cxa_begin_catch(i8*)
declare void @__cxa_end_catch()
declare void @__clang_call_terminate(i8*)
declare void @_ZSt9terminatev()
+
+attributes #0 = { nounwind }
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