[PATCH] D94995: Loop peeling: check that latch is conditional branch
Joseph Tremoulet via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 19 13:49:35 PST 2021
JosephTremoulet updated this revision to Diff 317684.
JosephTremoulet added a comment.
- Cast the terminator, not the block
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D94995/new/
https://reviews.llvm.org/D94995
Files:
llvm/lib/Transforms/Utils/LoopPeel.cpp
llvm/test/Transforms/LoopUnroll/peel-loop-conditions.ll
Index: llvm/test/Transforms/LoopUnroll/peel-loop-conditions.ll
===================================================================
--- llvm/test/Transforms/LoopUnroll/peel-loop-conditions.ll
+++ llvm/test/Transforms/LoopUnroll/peel-loop-conditions.ll
@@ -1140,5 +1140,35 @@
ret void
}
+; Invoke is not a conditional branch that we can optimize,
+; so this shouldn't be peeled at all. This is a reproducer
+; for a bug where evaluating the loop would fail an assertion.
+define void @test17() personality i8* undef{
+; CHECK-LABEL: @test17(
+; CHECK-NEXT: body:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[CONST:%.*]] = phi i64 [ -33, [[LOOP]] ], [ -20, [[BODY:%.*]] ]
+; CHECK-NEXT: invoke void @f1()
+; CHECK-NEXT: to label [[LOOP]] unwind label [[EH_UNW_LOOPEXIT:%.*]]
+; CHECK: eh.Unw.loopexit:
+; CHECK-NEXT: [[LPAD_LOOPEXIT:%.*]] = landingpad { i8*, i32 }
+; CHECK-NEXT: catch i8* null
+; CHECK-NEXT: ret void
+;
+body:
+ br label %loop
+
+loop:
+ %const = phi i64 [ -33, %loop ], [ -20, %body ]
+ invoke void @f1()
+ to label %loop unwind label %eh.Unw.loopexit
+
+eh.Unw.loopexit:
+ %lpad.loopexit = landingpad { i8*, i32 }
+ catch i8* null
+ ret void
+}
+
declare void @init()
declare void @sink()
Index: llvm/lib/Transforms/Utils/LoopPeel.cpp
===================================================================
--- llvm/lib/Transforms/Utils/LoopPeel.cpp
+++ llvm/lib/Transforms/Utils/LoopPeel.cpp
@@ -115,7 +115,12 @@
// This can be an indication of two different things:
// 1) The loop is not rotated.
// 2) The loop contains irreducible control flow that involves the latch.
- if (L->getLoopLatch() != L->getExitingBlock())
+ const BasicBlock *Latch = L->getLoopLatch();
+ if (Latch != L->getExitingBlock())
+ return false;
+
+ // Peeling is only supported if the latch is a conditional branch.
+ if (!isa<BranchInst>(Latch->getTerminator()))
return false;
return true;
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