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[Test] Add Loop Deletion test with irreducible CFG 

Authored by Mikael Holmén. It demonstrated miscompile on irreducible
CFG with patch "[LoopDeletion] Break backedge if we can prove that the loop is exited on 1st iteration".
The patch is reverted. Checking in the test to make sure this bug
does not return.
This commit is contained in:
Max Kazantsev 2021-05-26 18:35:30 +07:00
parent ba0fe85ec0
commit 5fb58d4598
1 changed files with 69 additions and 0 deletions
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69
llvm/test/Transforms/LoopDeletion/irreducible-cfg.ll Normal file
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -loop-deletion -S | FileCheck %s
; RUN: opt < %s -passes='loop(loop-deletion)' -S | FileCheck %s
; Make sure we do not get the miscompile on this test with irreducible CFG.
define i16 @test(i16 %j, i16 %k, i16 %recurs) { ; If we have %j: 1, %k: 1, %recurs: 0
; CHECK-LABEL: @test(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TOBOOL_NOT:%.*]] = icmp eq i16 [[RECURS:%.*]], 0
; CHECK-NEXT: br i1 [[TOBOOL_NOT]], label [[IF_END:%.*]], label [[IF_THEN:%.*]]
; CHECK: if.then:
; CHECK-NEXT: [[CALL:%.*]] = tail call i16 @test(i16 0, i16 0, i16 0)
; CHECK-NEXT: br label [[IF_END]]
; CHECK: if.end:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i16 [[J:%.*]], 0
; CHECK-NEXT: br label [[BB2:%.*]]
; CHECK: bb2:
; CHECK-NEXT: [[K_ADDR_0:%.*]] = phi i16 [ [[K:%.*]], [[IF_END]] ], [ [[K_ADDR_2:%.*]], [[BB12:%.*]] ]
; CHECK-NEXT: [[RESULT_0:%.*]] = phi i16 [ 0, [[IF_END]] ], [ 20, [[BB12]] ]
; CHECK-NEXT: br i1 [[CMP]], label [[BB12]], label [[BB4:%.*]]
; CHECK: bb4:
; CHECK-NEXT: [[K_ADDR_1:%.*]] = phi i16 [ [[K_ADDR_0]], [[BB2]] ], [ [[K_ADDR_2]], [[BB12]] ]
; CHECK-NEXT: [[X_1:%.*]] = phi i16 [ 0, [[BB2]] ], [ 1, [[BB12]] ]
; CHECK-NEXT: [[RESULT_1:%.*]] = phi i16 [ [[RESULT_0]], [[BB2]] ], [ 10, [[BB12]] ]
; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i16 [[K_ADDR_1]], 0
; CHECK-NEXT: br i1 [[CMP2]], label [[BB13:%.*]], label [[BB12]]
; CHECK: bb12:
; CHECK-NEXT: [[K_ADDR_2]] = phi i16 [ [[K_ADDR_0]], [[BB2]] ], [ 0, [[BB4]] ]
; CHECK-NEXT: [[X_2:%.*]] = phi i16 [ 1, [[BB2]] ], [ [[X_1]], [[BB4]] ]
; CHECK-NEXT: [[CMP5:%.*]] = icmp eq i16 [[X_2]], 0
; CHECK-NEXT: br i1 [[CMP5]], label [[BB2]], label [[BB4]]
; CHECK: bb13:
; CHECK-NEXT: [[RESULT_1_LCSSA:%.*]] = phi i16 [ [[RESULT_1]], [[BB4]] ]
; CHECK-NEXT: ret i16 [[RESULT_1_LCSSA]]
;
entry:
%tobool.not = icmp eq i16 %recurs, 0 ; 1
br i1 %tobool.not, label %if.end, label %if.then ; -> if.end
if.then: ; preds = %entry
%call = tail call i16 @test(i16 0, i16 0, i16 0)
br label %if.end
if.end: ; preds = %if.then, %entry
%cmp = icmp eq i16 %j, 0 ; 0
br label %bb2 ; -> bb2
bb2: ; preds = %bb12, %if.end
%k.addr.0 = phi i16 [ %k, %if.end ], [ %k.addr.2, %bb12 ] ; 1
%result.0 = phi i16 [ 0, %if.end ], [ 20, %bb12 ] ; 0
br i1 %cmp, label %bb12, label %bb4 ; %cmp: 0 -> bb4
bb4: ; preds = %bb12, %bb2
%k.addr.1 = phi i16 [ %k.addr.0, %bb2 ], [ %k.addr.2, %bb12 ] ; 1
%x.1 = phi i16 [ 0, %bb2 ], [ 1, %bb12 ] ; 0
%result.1 = phi i16 [ %result.0, %bb2 ], [ 10, %bb12 ]
%cmp2 = icmp eq i16 %k.addr.1, 0 ; 0
br i1 %cmp2, label %bb13, label %bb12 ; -> bb12
bb12: ; preds = %bb4, %bb2
%k.addr.2 = phi i16 [ %k.addr.0, %bb2 ], [ 0, %bb4 ] ; 0
%x.2 = phi i16 [ 1, %bb2 ], [ %x.1, %bb4 ] ; 0
%cmp5 = icmp eq i16 %x.2, 0 ; 1
br i1 %cmp5, label %bb2, label %bb4 ; -> bb2
bb13: ; preds = %bb4
%result.1.lcssa = phi i16 [ %result.1, %bb4 ]
ret i16 %result.1.lcssa
}