replica
/
hanchenye-llvm-project
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

[SEH] Push reloads of the SEH code past phi nodes 

This in turn would sometimes introduce new cleanupblocks that didn't
previously exist. The uses were being introduced by SSA value demotion.
We actually want to *promote* uses of EH pointers and selectors, so I
added some spcecial casing to avoid demoting such instructions.  This is
getting overly complicated, but hopefully we'll come along and delete it
in the new representation.

llvm-svn: 241950
This commit is contained in:
Reid Kleckner 2015-07-10 22:21:54 +00:00
parent f787ed0b35
commit 7ea7708d92
2 changed files with 119 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
llvm/lib/CodeGen/WinEHPrepare.cpp
View File

@ -616,6 +616,26 @@ void WinEHPrepare::demoteValuesLiveAcrossHandlers(
// identifyEHBlocks() should have been called before this function.
assert(!NormalBlocks.empty());
// Try to avoid demoting EH pointer and selector values. They get in the way
// of our pattern matching.
SmallPtrSet<Instruction *, 10> EHVals;
for (BasicBlock &BB : F) {
LandingPadInst *LP = BB.getLandingPadInst();
if (!LP)
continue;
EHVals.insert(LP);
for (User *U : LP->users()) {
auto *EI = dyn_cast<ExtractValueInst>(U);
if (!EI)
continue;
EHVals.insert(EI);
for (User *U2 : EI->users()) {
if (auto *PN = dyn_cast<PHINode>(U2))
EHVals.insert(PN);
}
}
}
SetVector<Argument *> ArgsToDemote;
SetVector<Instruction *> InstrsToDemote;
for (BasicBlock &BB : F) {
@ -641,7 +661,11 @@ void WinEHPrepare::demoteValuesLiveAcrossHandlers(
continue;
}
// Don't demote EH values.
auto *OpI = cast<Instruction>(Op);
if (EHVals.count(OpI))
continue;
BasicBlock *OpBB = OpI->getParent();
// If a value is produced and consumed in the same BB, we don't need to
// demote it.
@ -822,7 +846,8 @@ bool WinEHPrepare::prepareExceptionHandlers(
LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));
// Rewrite uses of the exception pointer to loads of an alloca.
for (Instruction *E : SEHCodeUses) {
while (!SEHCodeUses.empty()) {
Instruction *E = SEHCodeUses.pop_back_val();
SmallVector<Use *, 4> Uses;
for (Use &U : E->uses())
Uses.push_back(&U);
@ -830,13 +855,10 @@ bool WinEHPrepare::prepareExceptionHandlers(
auto *I = cast<Instruction>(U->getUser());
if (isa<ResumeInst>(I))
continue;
LoadInst *LI;
if (auto *Phi = dyn_cast<PHINode>(I))
LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false,
Phi->getIncomingBlock(*U)->getTerminator());
SEHCodeUses.push_back(Phi);
else
LI = new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I);
U->set(LI);
U->set(new LoadInst(SEHExceptionCodeSlot, "sehcode", false, I));
}
E->replaceAllUsesWith(UndefValue::get(E->getType()));
E->eraseFromParent();

91
llvm/test/CodeGen/WinEH/seh-exception-code2.ll Normal file
View File

@ -0,0 +1,91 @@
; RUN: opt -winehprepare -S < %s | FileCheck %s
; WinEHPrepare was crashing during phi demotion.
target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-windows-msvc18.0.0"
declare i32 @__C_specific_handler(...)
@str = linkonce_odr unnamed_addr constant [16 x i8] c"caught it! %lx\0A\00", align 1
declare void @maycrash()
declare void @finally(i1 %abnormal)
declare i32 @printf(i8* nocapture readonly, ...)
declare i32 @llvm.eh.typeid.for(i8*)
; Function Attrs: nounwind uwtable
define void @doit() personality i8* bitcast (i32 (...)* @__C_specific_handler to i8*) {
entry:
invoke void @maycrash()
to label %invoke.cont unwind label %lpad.1
invoke.cont: ; preds = %entry
invoke void @maycrash()
to label %__try.cont unwind label %lpad
lpad: ; preds = %entry
%lp0 = landingpad { i8*, i32 }
cleanup
catch i8* bitcast (i32 (i8*, i8*)* @"\01?filt$0@0@doit@@" to i8*)
%ehptr.0 = extractvalue { i8*, i32 } %lp0, 0
%ehsel.0 = extractvalue { i8*, i32 } %lp0, 1
call void @finally(i1 true)
br label %ehdispatch
lpad.1: ; preds = %invoke.cont, %lpad
%lp1 = landingpad { i8*, i32 }
catch i8* bitcast (i32 (i8*, i8*)* @"\01?filt$0@0@doit@@" to i8*)
%ehptr.1 = extractvalue { i8*, i32 } %lp1, 0
%ehsel.1 = extractvalue { i8*, i32 } %lp1, 1
br label %ehdispatch
ehdispatch:
%ehptr.2 = phi i8* [ %ehptr.0, %lpad ], [ %ehptr.1, %lpad.1 ]
%ehsel.2 = phi i32 [ %ehsel.0, %lpad ], [ %ehsel.1, %lpad.1 ]
%mysel = call i32 @llvm.eh.typeid.for(i8* bitcast (i32 (i8*, i8*)* @"\01?filt$0@0@doit@@" to i8*))
%matches = icmp eq i32 %ehsel.2, %mysel
br i1 %matches, label %__except, label %eh.resume
__except: ; preds = %lpad, %lpad.1
%t4 = ptrtoint i8* %ehptr.2 to i64
%t5 = trunc i64 %t4 to i32
%call = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([16 x i8], [16 x i8]* @str, i64 0, i64 0), i32 %t5)
br label %__try.cont
__try.cont: ; preds = %invoke.cont, %__except
call void @finally(i1 false)
ret void
eh.resume:
%ehvals0 = insertvalue { i8*, i32 } undef, i8* %ehptr.2, 0
%ehvals = insertvalue { i8*, i32 } %ehvals0, i32 %ehsel.2, 1
resume { i8*, i32 } %ehvals
}
define internal i32 @"\01?filt$0@0@doit@@"(i8* %exception_pointers, i8* %frame_pointer) #1 {
entry:
%0 = bitcast i8* %exception_pointers to { i32*, i8* }*
%1 = getelementptr inbounds { i32*, i8* }, { i32*, i8* }* %0, i32 0, i32 0
%2 = load i32*, i32** %1
%3 = load i32, i32* %2
%cmp = icmp eq i32 %3, -1073741819
%4 = zext i1 %cmp to i32
ret i32 %4
}
; CHECK-LABEL: define void @doit()
; CHECK: %lp0 = landingpad { i8*, i32 }
; CHECK-NEXT: cleanup
; CHECK-NEXT: catch i8*
; CHECK-NEXT: call i8* (...) @llvm.eh.actions({{.*}})
; CHECK-NEXT: indirectbr i8* %{{[^,]*}}, [label %__except]
;
; CHECK: %lp1 = landingpad { i8*, i32 }
; CHECK-NEXT: catch i8*
; CHECK-NEXT: call i8* (...) @llvm.eh.actions({{.*}})
; CHECK-NEXT: indirectbr i8* %{{[^,]*}}, [label %__except]
;
; CHECK: __except:
; CHECK: call i32 @llvm.eh.exceptioncode()
; CHECK: call i32 (i8*, ...) @printf