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[Coroutines] Add missing llvm.dbg.declare's to cover for more allocas
Tracking local variables across suspend points is still somewhat incomplete.
Consider this coroutine snippet:
```
resumable foo() {
int x[10] = {};
int a = 3;
co_await std::experimental::suspend_always();
a++;
x[0] = 1;
a += 2;
x[1] = 2;
a += 3;
x[2] = 3;
}
```
Can't manage to print `a` or `x` if they turn out to be allocas during
CoroSplit (which happens if you build this code with `-O0` prior to this
commit):
```
* thread #1, queue = 'com.apple.main-thread', stop reason = step over
frame #0: 0x0000000100003729 main-noprint`foo() at main-noprint.cpp:43:5
40 co_await std::experimental::suspend_always();
41 a++;
42 x[0] = 1;
-> 43 a += 2;
44 x[1] = 2;
45 a += 3;
46 x[2] = 3;
(lldb) p x
error: <user expression 21>:1:1: use of undeclared identifier 'x'
x
^
```
The generated IR contains a `llvm.dbg.declare` for `x` in it's initialization
basic block. After CoroSplit, the `llvm.dbg.declare` might not dominate all of
`x` uses and we lose debugging quality.
Add `llvm.dbg.value`s to all relevant basic blocks such that if later
transformations break the dominance the reliable debug info is already in
place. For instance, this BB:
```
await.ready:
...
%arrayidx = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 0, !dbg !760
...
%arrayidx19 = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 1, !dbg !763
...
%arrayidx21 = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 2, !dbg !766
```
becomes:
```
await.ready:
...
call void @llvm.dbg.value(metadata [10 x i32]* %x.reload.addr, metadata !751, metadata !DIExpression()), !dbg !753
...
%arrayidx = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 0, !dbg !760
...
%arrayidx19 = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 1, !dbg !763
...
%arrayidx21 = getelementptr inbounds [10 x i32], [10 x i32]* %x.reload.addr, i64 0, i64 2, !dbg !766
```
Differential Revision: https://reviews.llvm.org/D90772
This commit is contained in:
Bruno Cardoso Lopes
parent
2b47fb5801
commit
c9218bd12a
@ -1191,19 +1191,51 @@ static Instruction *insertSpills(const FrameDataInfo &FrameData,
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continue;
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auto *G = GetFramePointer(Alloca);
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G->setName(Alloca->getName() + Twine(".reload.addr"));
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SmallPtrSet<BasicBlock *, 4> SeenDbgBBs;
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TinyPtrVector<DbgDeclareInst *> DIs = FindDbgDeclareUses(Alloca);
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if (!DIs.empty())
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DIBuilder(*Alloca->getModule(),
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/*AllowUnresolved*/ false)
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.insertDeclare(G, DIs.front()->getVariable(),
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DIs.front()->getExpression(),
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DIs.front()->getDebugLoc(), DIs.front());
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DIBuilder DIB(*Alloca->getModule(), /*AllowUnresolved*/ false);
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Instruction *FirstDbgDecl = nullptr;
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if (!DIs.empty()) {
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FirstDbgDecl = DIB.insertDeclare(G, DIs.front()->getVariable(),
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DIs.front()->getExpression(),
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DIs.front()->getDebugLoc(), DIs.front());
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SeenDbgBBs.insert(DIs.front()->getParent());
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}
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for (auto *DI : FindDbgDeclareUses(Alloca))
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DI->eraseFromParent();
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replaceDbgUsesWithUndef(Alloca);
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for (Instruction *I : UsersToUpdate)
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for (Instruction *I : UsersToUpdate) {
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I->replaceUsesOfWith(Alloca, G);
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// After cloning, transformations might not guarantee that all uses
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// of this alloca are dominated by the already existing dbg.declare's,
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// compromising the debug quality. Instead of writing another
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// transformation to patch each clone, go ahead and early populate
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// basic blocks that use such allocas with more debug info.
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if (SeenDbgBBs.count(I->getParent()))
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continue;
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// If there isn't a prior dbg.declare for this alloca, it probably
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// means the state hasn't changed prior to one of the relevant suspend
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// point for this frame access.
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if (!FirstDbgDecl)
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continue;
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// These instructions are all dominated by the alloca, insert the
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// dbg.value in the beginning of the BB to enhance debugging
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// experience and allow values to be inspected as early as possible.
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// Prefer dbg.value over dbg.declare since it better sets expectations
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// that control flow can be later changed by other passes.
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auto *DI = cast<DbgDeclareInst>(FirstDbgDecl);
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BasicBlock *CurrentBlock = I->getParent();
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DIB.insertDbgValueIntrinsic(G, DI->getVariable(), DI->getExpression(),
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DI->getDebugLoc(),
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&*CurrentBlock->getFirstInsertionPt());
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SeenDbgBBs.insert(CurrentBlock);
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}
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}
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Builder.SetInsertPoint(FramePtr->getNextNode());
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for (const auto &A : FrameData.Allocas) {
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@ -7,15 +7,19 @@
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; void foo() {
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; int i = 0;
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; ++i;
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; int x = {};
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; print(i); // Prints '1'
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;
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; co_await suspend_always();
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;
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; int j = 0;
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; x[0] = 1;
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; x[1] = 2;
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; ++i;
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; print(i); // Prints '2'
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; ++j;
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; print(j); // Prints '1'
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; print(x); // Print '1'
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; }
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;
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; The CHECKs verify that dbg.declare intrinsics are created for the coroutine
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@ -28,28 +32,39 @@
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; CHECK: entry:
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; CHECK: %j = alloca i32, align 4
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; CHECK: [[IGEP:%.+]] = getelementptr inbounds %f.Frame, %f.Frame* %FramePtr, i32 0, i32 4
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; CHECK: [[XGEP:%.+]] = getelementptr inbounds %f.Frame, %f.Frame* %FramePtr, i32 0, i32 6
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; CHECK: init.ready:
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; CHECK: call void @llvm.dbg.declare(metadata i32* [[IGEP]], metadata ![[IVAR:[0-9]+]], metadata !DIExpression()), !dbg ![[IDBGLOC:[0-9]+]]
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; CHECK: call void @llvm.dbg.declare(metadata [10 x i32]* [[XGEP]], metadata ![[XVAR:[0-9]+]], metadata !DIExpression()), !dbg ![[IDBGLOC]]
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; CHECK: await.ready:
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; CHECK: call void @llvm.dbg.value(metadata [10 x i32]* [[XGEP]], metadata ![[XVAR]], metadata !DIExpression()), !dbg ![[IDBGLOC]]
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; CHECK: call void @llvm.dbg.value(metadata i32* [[IGEP]], metadata ![[IVAR]], metadata !DIExpression()), !dbg ![[IDBGLOC]]
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; CHECK: call void @llvm.dbg.declare(metadata i32* %j, metadata ![[JVAR:[0-9]+]], metadata !DIExpression()), !dbg ![[JDBGLOC:[0-9]+]]
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;
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; CHECK-LABEL: define internal fastcc void @f.resume({{.*}}) {
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; CHECK: entry.resume:
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; CHECK: %j = alloca i32, align 4
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; CHECK: [[IGEP_RESUME:%.+]] = getelementptr inbounds %f.Frame, %f.Frame* %FramePtr, i32 0, i32 4
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; CHECK: [[XGEP_RESUME:%.+]] = getelementptr inbounds %f.Frame, %f.Frame* %FramePtr, i32 0, i32 6
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; CHECK: init.ready:
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; CHECK: call void @llvm.dbg.declare(metadata i32* [[IGEP_RESUME]], metadata ![[IVAR_RESUME:[0-9]+]], metadata !DIExpression()), !dbg ![[IDBGLOC_RESUME:[0-9]+]]
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; CHECK: call void @llvm.dbg.declare(metadata [10 x i32]* [[XGEP_RESUME]], metadata ![[XVAR_RESUME:[0-9]+]], metadata !DIExpression()), !dbg ![[IDBGLOC_RESUME]]
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; CHECK: await.ready:
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; CHECK: call void @llvm.dbg.value(metadata [10 x i32]* [[XGEP_RESUME]], metadata ![[XVAR_RESUME]], metadata !DIExpression()), !dbg ![[IDBGLOC_RESUME]]
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; CHECK: call void @llvm.dbg.value(metadata i32* [[IGEP_RESUME]], metadata ![[IVAR_RESUME]], metadata !DIExpression()), !dbg ![[IDBGLOC_RESUME]]
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; CHECK: call void @llvm.dbg.declare(metadata i32* %j, metadata ![[JVAR_RESUME:[0-9]+]], metadata !DIExpression()), !dbg ![[JDBGLOC_RESUME:[0-9]+]]
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;
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; CHECK: ![[IVAR]] = !DILocalVariable(name: "i"
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; CHECK: ![[SCOPE:[0-9]+]] = distinct !DILexicalBlock(scope: !8, file: !1, line: 23, column: 12)
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; CHECK: ![[IDBGLOC]] = !DILocation(line: 24, column: 7, scope: ![[SCOPE]])
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; CHECK: ![[XVAR]] = !DILocalVariable(name: "x"
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; CHECK: ![[JVAR]] = !DILocalVariable(name: "j"
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; CHECK: ![[JDBGLOC]] = !DILocation(line: 32, column: 7, scope: ![[SCOPE]])
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; CHECK: ![[IVAR_RESUME]] = !DILocalVariable(name: "i"
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; CHECK: ![[RESUME_SCOPE:[0-9]+]] = distinct !DILexicalBlock(scope: !8, file: !1, line: 23, column: 12)
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; CHECK: ![[IDBGLOC_RESUME]] = !DILocation(line: 24, column: 7, scope: ![[RESUME_SCOPE]])
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; CHECK: ![[XVAR_RESUME]] = !DILocalVariable(name: "x"
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; CHECK: ![[JVAR_RESUME]] = !DILocalVariable(name: "j"
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; CHECK: ![[JDBGLOC_RESUME]] = !DILocation(line: 32, column: 7, scope: ![[RESUME_SCOPE]])
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define void @f() {
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@ -57,6 +72,7 @@ entry:
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%__promise = alloca i8, align 8
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%i = alloca i32, align 4
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%j = alloca i32, align 4
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%x = alloca [10 x i32], align 16
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%id = call token @llvm.coro.id(i32 16, i8* %__promise, i8* null, i8* null)
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%alloc = call i1 @llvm.coro.alloc(token %id)
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br i1 %alloc, label %coro.alloc, label %coro.init
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@ -91,6 +107,9 @@ init.ready: ; preds = %init.suspend, %coro
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%i.init.ready.load = load i32, i32* %i, align 4
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%i.init.ready.inc = add nsw i32 %i.init.ready.load, 1
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store i32 %i.init.ready.inc, i32* %i, align 4
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call void @llvm.dbg.declare(metadata [10 x i32]* %x, metadata !14, metadata !DIExpression()), !dbg !11
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%memset = bitcast [10 x i32]* %x to i8*, !dbg !11
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call void @llvm.memset.p0i8.i64(i8* align 16 %memset, i8 0, i64 40, i1 false), !dbg !11
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%i.init.ready.reload = load i32, i32* %i, align 4
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call void @print(i32 %i.init.ready.reload)
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%ready.again = call zeroext i1 @await_ready()
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@ -113,6 +132,10 @@ await.ready: ; preds = %await.suspend, %ini
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call void @await_resume()
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call void @llvm.dbg.declare(metadata i32* %j, metadata !12, metadata !DIExpression()), !dbg !13
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store i32 0, i32* %j, align 4
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%arrayidx0 = getelementptr inbounds [10 x i32], [10 x i32]* %x, i64 0, i64 0, !dbg !18
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store i32 1, i32* %arrayidx0, align 16, !dbg !19
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%arrayidx1 = getelementptr inbounds [10 x i32], [10 x i32]* %x, i64 0, i64 1, !dbg !20
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store i32 2, i32* %arrayidx1, align 4, !dbg !21
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%i.await.ready.load = load i32, i32* %i, align 4
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%i.await.ready.inc = add nsw i32 %i.await.ready.load, 1
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store i32 %i.await.ready.inc, i32* %i, align 4
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@ -195,6 +218,8 @@ declare i8* @from_address(i8*)
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declare void @return_void()
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declare void @final_suspend()
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declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1 immarg)
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!llvm.dbg.cu = !{!0}
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!llvm.linker.options = !{}
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!llvm.module.flags = !{!3, !4}
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@ -214,3 +239,12 @@ declare void @final_suspend()
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!11 = !DILocation(line: 24, column: 7, scope: !7)
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!12 = !DILocalVariable(name: "j", scope: !7, file: !1, line: 32, type: !10)
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!13 = !DILocation(line: 32, column: 7, scope: !7)
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!14 = !DILocalVariable(name: "x", scope: !22, file: !1, line: 34, type: !15)
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!15 = !DICompositeType(tag: DW_TAG_array_type, baseType: !10, size: 320, elements: !16)
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!16 = !{!17}
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!17 = !DISubrange(count: 10)
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!18 = !DILocation(line: 42, column: 3, scope: !7)
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!19 = !DILocation(line: 42, column: 8, scope: !7)
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!20 = !DILocation(line: 43, column: 3, scope: !7)
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!21 = !DILocation(line: 43, column: 8, scope: !7)
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!22 = distinct !DILexicalBlock(scope: !8, file: !1, line: 23, column: 12)
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