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GorNishanovGorNishanov
committedSep 5, 2016
[Coroutines] Part12: Handle alloca address-taken
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
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‎llvm/lib/Transforms/Coroutines/CoroFrame.cpp

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

‎llvm/test/Transforms/Coroutines/ArgAddr.ll

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

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