4495a6b141
This patch adds a new option to CriticalEdgeSplittingOptions to control
whether loop-simplify form must be preserved. It is them used by GVN to
indicate that loop-simplify form does not have to be preserved.
This fixes a crash exposed by 189efe295b.
If the critical edge we are splitting goes from a block inside a loop to
a block outside the loop, splitting the edge will create a new exit
block. As a result, the new block will branch to the original exit
block, which will add a non-loop predecessor, breaking loop-simplify
form. To preserve loop-simplify form, the predecessor blocks of the
original exit are split, but that does not work for blocks with
indirectbr terminators. If preserving loop-simplify form is requested,
bail out , before making any changes.
Reviewers: reames, hfinkel, davide, efriedma
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D81582
47 lines
1.8 KiB
LLVM
47 lines
1.8 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -gvn -S -verify-loop-info %s | FileCheck %s
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; Make sure we do not try to preserve loop-simplify form, if it would mean
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; splitting blocks with indirectbr predecessors.
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declare i1 @cond()
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define i32 @foo(i8* %p1, i8* %p2, i32* %p3) {
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; CHECK-LABEL: @foo(
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; CHECK-NEXT: bb:
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; CHECK-NEXT: br label [[LOOP_HEADER:%.*]]
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; CHECK: loop.header:
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; CHECK-NEXT: store i32 0, i32* [[P3:%.*]], align 4
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; CHECK-NEXT: indirectbr i8* [[P1:%.*]], [label [[LOOP_LATCH1:%.*]], label %loop.latch2]
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; CHECK: loop.latch1:
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; CHECK-NEXT: [[C:%.*]] = call i1 @cond()
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; CHECK-NEXT: br i1 [[C]], label [[LOOP_HEADER]], label [[LOOP_LATCH1_EXIT_CRIT_EDGE:%.*]]
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; CHECK: loop.latch1.exit_crit_edge:
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; CHECK-NEXT: [[X_PRE:%.*]] = load i32, i32* [[P3]], align 4
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; CHECK-NEXT: br label [[EXIT:%.*]]
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; CHECK: loop.latch2:
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; CHECK-NEXT: indirectbr i8* [[P2:%.*]], [label [[LOOP_HEADER]], label %exit]
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; CHECK: exit:
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; CHECK-NEXT: [[X:%.*]] = phi i32 [ [[X_PRE]], [[LOOP_LATCH1_EXIT_CRIT_EDGE]] ], [ 0, [[LOOP_LATCH2:%.*]] ]
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; CHECK-NEXT: ret i32 [[X]]
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;
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bb:
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br label %loop.header
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loop.header: ; preds = %loop.latch2, %loop.latch1, %bb
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store i32 0, i32* %p3, align 4
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indirectbr i8* %p1, [label %loop.latch1, label %loop.latch2]
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loop.latch1: ; preds = %loop.header
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%c = call i1 @cond()
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br i1 %c, label %loop.header, label %exit
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loop.latch2: ; preds = %loop.header
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indirectbr i8* %p2, [label %loop.header, label %exit]
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exit: ; preds = %loop.latch2, %loop.latch1
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%x = load i32, i32* %p3, align 4
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%y = add i32 %x, 0
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ret i32 %y
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}
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