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llvm-mirror/test/Transforms/GVN/preserve-analysis.ll
Florian Hahn e1717245c4 [BreakCritEdges] Add option to opt-out of perserving loop-simplify.
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 189efe295b6e.

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
2020-06-12 11:47:13 +01:00

57 lines
1.5 KiB
LLVM

; RUN: opt < %s -debug-pass=Structure -indvars -gvn -indvars 2>&1 -S | FileCheck --check-prefix=CHECK --check-prefix=IR %s
; RUN: opt < %s -debug-pass-manager -passes='require<domtree>,loop(simplify-cfg),gvn,loop(indvars)' 2>&1 -S | FileCheck --check-prefix=NEW-PM --check-prefix=IR %s
; Check CFG-only analysis are preserved by SCCP by running it between 2
; loop-vectorize runs.
; CHECK: Dominator Tree Construction
; CHECK: Natural Loop Information
; CHECK: Canonicalize natural loops
; CHECK: LCSSA Verifier
; CHECK: Loop-Closed SSA Form Pass
; CHECK: Global Value Numbering
; CHECK-NOT: Dominator Tree Construction
; CHECK-NOT: Natural Loop Information
; CHECK: Canonicalize natural loops
; NEW-PM-DAG: Running analysis: LoopAnalysis on test
; NEW-PM-DAG: Running analysis: DominatorTreeAnalysis on test
; NEW-PM: Running pass: GVN on test
; NEW-PM-NOT: Running analysis: LoopAnalysis on test
; NEW-PM-NOT: Running analysis: DominatorTreeAnalysis on test
declare i1 @cond()
declare void @dostuff()
define i32 @test() {
; IR-LABEL: define i32 @test()
; IR-LABEL: header:
; IR: br i1 false, label %then, label %latch
; IR-LABEL: then:
; IR-NEXT: call void @dostuff()
; IR-NEXT: br label %latch
entry:
%res = add i32 1, 10
br label %header
header:
%iv = phi i32 [ %res, %entry ], [ 0, %latch ]
%ic = icmp eq i32 %res, 99
br i1 %ic, label %then, label %latch
then:
br label %then.2
then.2:
call void @dostuff()
br label %latch
latch:
%ec = call i1 @cond()
br i1 %ec, label %exit, label %header
exit:
ret i32 %iv
}