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[Coroutines] Part12: Handle alloca address-taken

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Summary:
Move early uses of spilled variables after CoroBegin.

For example, if a parameter had address taken, we may end up with the code
like:
        define @f(i32 %n) {
          %n.addr = alloca i32
          store %n, %n.addr
          ...
          call @coro.begin

This patch fixes the problem by moving uses of spilled variables after CoroBegin.

Reviewers: majnemer

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D24234

llvm-svn: 280678
This commit is contained in:
Gor Nishanov 2016-09-05 23:45:45 +00:00
parent cecaa24855
commit 47343c589d
2 changed files with 113 additions and 1 deletions
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47
lib/Transforms/Coroutines/CoroFrame.cpp
View File

@ -560,6 +560,51 @@ static void rewriteMaterializableInstructions(IRBuilder<> &IRB,
}
}
// Move early uses of spilled variable after CoroBegin.
// For example, if a parameter had address taken, we may end up with the code
// like:
// define @f(i32 %n) {
// %n.addr = alloca i32
// store %n, %n.addr
// ...
// call @coro.begin
// we need to move the store after coro.begin
static void moveSpillUsesAfterCoroBegin(Function &F, SpillInfo const &Spills,
CoroBeginInst *CoroBegin) {
DominatorTree DT(F);
SmallVector<Instruction *, 8> NeedsMoving;
Value *CurrentValue = nullptr;
for (auto const &E : Spills) {
if (CurrentValue == E.def())
continue;
CurrentValue = E.def();
for (User *U : CurrentValue->users()) {
Instruction *I = cast<Instruction>(U);
if (!DT.dominates(CoroBegin, I)) {
// TODO: Make this more robust. Currently if we run into a situation
// where simple instruction move won't work we panic and
// report_fatal_error.
for (User *UI : I->users()) {
if (!DT.dominates(CoroBegin, cast<Instruction>(UI)))
report_fatal_error("cannot move instruction since its users are not"
" dominated by CoroBegin");
}
DEBUG(dbgs() << "will move: " << *I << "\n");
NeedsMoving.push_back(I);
}
}
}
Instruction *InsertPt = CoroBegin->getNextNode();
for (Instruction *I : NeedsMoving)
I->moveBefore(InsertPt);
}
// Splits the block at a particular instruction unless it is the first
// instruction in the block with a single predecessor.
static BasicBlock *splitBlockIfNotFirst(Instruction *I, const Twine &Name) {
@ -656,7 +701,7 @@ void coro::buildCoroutineFrame(Function &F, Shape &Shape) {
}
std::sort(Spills.begin(), Spills.end());
DEBUG(dump("Spills", Spills));
moveSpillUsesAfterCoroBegin(F, Spills, Shape.CoroBegin);
Shape.FrameTy = buildFrameType(F, Shape, Spills);
Shape.FramePtr = insertSpills(Spills, Shape);
}

67
test/Transforms/Coroutines/ArgAddr.ll Normal file
View File

@ -0,0 +1,67 @@
; Need to move users of allocas that were moved into the coroutine frame after
; coro.begin.
; RUN: opt < %s -O2 -enable-coroutines -S | FileCheck %s
define nonnull i8* @f(i32 %n) {
entry:
%id = call token @llvm.coro.id(i32 0, i8* null, i8* null, i8* null);
%n.addr = alloca i32
store i32 %n, i32* %n.addr ; this needs to go after coro.begin
%0 = tail call i32 @llvm.coro.size.i32()
%call = tail call i8* @malloc(i32 %0)
%1 = tail call noalias nonnull i8* @llvm.coro.begin(token %id, i8* %call)
%2 = bitcast i32* %n.addr to i8*
call void @ctor(i8* %2)
br label %for.cond
for.cond:
%3 = load i32, i32* %n.addr
%dec = add nsw i32 %3, -1
store i32 %dec, i32* %n.addr
call void @print(i32 %3)
%4 = call i8 @llvm.coro.suspend(token none, i1 false)
%conv = sext i8 %4 to i32
switch i32 %conv, label %coro_Suspend [
i32 0, label %for.cond
i32 1, label %coro_Cleanup
]
coro_Cleanup:
%5 = call i8* @llvm.coro.free(token %id, i8* nonnull %1)
call void @free(i8* %5)
br label %coro_Suspend
coro_Suspend:
call void @llvm.coro.end(i8* null, i1 false)
ret i8* %1
}
; CHECK-LABEL: @main
define i32 @main() {
entry:
%hdl = call i8* @f(i32 4)
call void @llvm.coro.resume(i8* %hdl)
call void @llvm.coro.resume(i8* %hdl)
call void @llvm.coro.destroy(i8* %hdl)
ret i32 0
; CHECK: call void @ctor
; CHECK-NEXT: call void @print(i32 4)
; CHECK-NEXT: call void @print(i32 3)
; CHECK-NEXT: call void @print(i32 2)
; CHECK: ret i32 0
}
declare i8* @malloc(i32)
declare void @free(i8*)
declare void @print(i32)
declare void @ctor(i8* nocapture readonly)
declare token @llvm.coro.id(i32, i8*, i8*, i8*)
declare i32 @llvm.coro.size.i32()
declare i8* @llvm.coro.begin(token, i8*)
declare i8 @llvm.coro.suspend(token, i1)
declare i8* @llvm.coro.free(token, i8*)
declare void @llvm.coro.end(i8*, i1)
declare void @llvm.coro.resume(i8*)
declare void @llvm.coro.destroy(i8*)