[llvm] r374703 - [Attributor][FIX] Avoid splitting blocks if possible
Johannes Doerfert via llvm-commits
llvm-commits at lists.llvm.org
Sat Oct 12 22:27:09 PDT 2019
Author: jdoerfert
Date: Sat Oct 12 22:27:09 2019
New Revision: 374703
URL: http://llvm.org/viewvc/llvm-project?rev=374703&view=rev
Log:
[Attributor][FIX] Avoid splitting blocks if possible
Before, we eagerly split blocks even if it was not necessary, e.g., they
had a single unreachable instruction and only a single predecessor.
Modified:
llvm/trunk/lib/Transforms/IPO/Attributor.cpp
llvm/trunk/test/Transforms/FunctionAttrs/liveness.ll
llvm/trunk/test/Transforms/FunctionAttrs/noreturn_async.ll
llvm/trunk/test/Transforms/FunctionAttrs/noreturn_sync.ll
Modified: llvm/trunk/lib/Transforms/IPO/Attributor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/Attributor.cpp?rev=374703&r1=374702&r2=374703&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/Attributor.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/Attributor.cpp Sat Oct 12 22:27:09 2019
@@ -2139,8 +2139,6 @@ struct AAIsDeadImpl : public AAIsDead {
BasicBlock *BB = I->getParent();
Instruction *SplitPos = I->getNextNode();
// TODO: mark stuff before unreachable instructions as dead.
- if (isa_and_nonnull<UnreachableInst>(SplitPos))
- continue;
if (auto *II = dyn_cast<InvokeInst>(I)) {
// If we keep the invoke the split position is at the beginning of the
@@ -2183,15 +2181,23 @@ struct AAIsDeadImpl : public AAIsDead {
// also manifest.
assert(!NormalDestBB->isLandingPad() &&
"Expected the normal destination not to be a landingpad!");
- BasicBlock *SplitBB =
- SplitBlockPredecessors(NormalDestBB, {BB}, ".dead");
- // The split block is live even if it contains only an unreachable
- // instruction at the end.
- assumeLive(A, *SplitBB);
- SplitPos = SplitBB->getTerminator();
+ if (NormalDestBB->getUniquePredecessor() == BB) {
+ assumeLive(A, *NormalDestBB);
+ } else {
+ BasicBlock *SplitBB =
+ SplitBlockPredecessors(NormalDestBB, {BB}, ".dead");
+ // The split block is live even if it contains only an unreachable
+ // instruction at the end.
+ assumeLive(A, *SplitBB);
+ SplitPos = SplitBB->getTerminator();
+ HasChanged = ChangeStatus::CHANGED;
+ }
}
}
+ if (isa_and_nonnull<UnreachableInst>(SplitPos))
+ continue;
+
BB = SplitPos->getParent();
SplitBlock(BB, SplitPos);
changeToUnreachable(BB->getTerminator(), /* UseLLVMTrap */ false);
Modified: llvm/trunk/test/Transforms/FunctionAttrs/liveness.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/liveness.ll?rev=374703&r1=374702&r2=374703&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/FunctionAttrs/liveness.ll (original)
+++ llvm/trunk/test/Transforms/FunctionAttrs/liveness.ll Sat Oct 12 22:27:09 2019
@@ -177,7 +177,7 @@ cond.true:
%call = invoke i32 @foo_noreturn() to label %continue
unwind label %cleanup
; CHECK: %call = invoke i32 @foo_noreturn()
- ; CHECK-NEXT: to label %continue.dead unwind label %cleanup
+ ; CHECK-NEXT: to label %continue unwind label %cleanup
cond.false: ; preds = %entry
call void @normal_call()
@@ -189,7 +189,7 @@ cond.end:
ret i32 %cond
continue:
- ; CHECK: continue.dead:
+ ; CHECK: continue:
; CHECK-NEXT: unreachable
br label %cond.end
Modified: llvm/trunk/test/Transforms/FunctionAttrs/noreturn_async.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/noreturn_async.ll?rev=374703&r1=374702&r2=374703&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/FunctionAttrs/noreturn_async.ll (original)
+++ llvm/trunk/test/Transforms/FunctionAttrs/noreturn_async.ll Sat Oct 12 22:27:09 2019
@@ -42,12 +42,12 @@ entry:
%retval = alloca i32, align 4
%__exception_code = alloca i32, align 4
; CHECK: invoke void @"?overflow@@YAXXZ"()
-; CHECK: to label %invoke.cont.dead unwind label %catch.dispatch
+; CHECK: to label %invoke.cont unwind label %catch.dispatch
invoke void @"?overflow@@YAXXZ"()
to label %invoke.cont unwind label %catch.dispatch
invoke.cont: ; preds = %entry
-; CHECK: invoke.cont.dead:
+; CHECK: invoke.cont:
; CHECK-NEXT: unreachable
br label %invoke.cont1
@@ -101,12 +101,12 @@ entry:
%retval = alloca i32, align 4
%__exception_code = alloca i32, align 4
; CHECK: invoke void @"?overflow@@YAXXZ_may_throw"()
-; CHECK: to label %invoke.cont.dead unwind label %catch.dispatch
+; CHECK: to label %invoke.cont unwind label %catch.dispatch
invoke void @"?overflow@@YAXXZ_may_throw"()
to label %invoke.cont unwind label %catch.dispatch
invoke.cont: ; preds = %entry
-; CHECK: invoke.cont.dead:
+; CHECK: invoke.cont:
; CHECK-NEXT: unreachable
br label %invoke.cont1
Modified: llvm/trunk/test/Transforms/FunctionAttrs/noreturn_sync.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/noreturn_sync.ll?rev=374703&r1=374702&r2=374703&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/FunctionAttrs/noreturn_sync.ll (original)
+++ llvm/trunk/test/Transforms/FunctionAttrs/noreturn_sync.ll Sat Oct 12 22:27:09 2019
@@ -97,12 +97,12 @@ entry:
%retval = alloca i32, align 4
%__exception_code = alloca i32, align 4
; CHECK: invoke void @"?overflow@@YAXXZ_may_throw"()
-; CHECK: to label %invoke.cont.dead unwind label %catch.dispatch
+; CHECK: to label %invoke.cont unwind label %catch.dispatch
invoke void @"?overflow@@YAXXZ_may_throw"()
to label %invoke.cont unwind label %catch.dispatch
invoke.cont: ; preds = %entry
-; CHECK: invoke.cont.dead:
+; CHECK: invoke.cont:
; CHECK-NEXT: unreachable
br label %invoke.cont1
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