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[SimplifyCFG] add test to show miscompile from FoldBranchToCommonDest (PR51125); NFC

This commit is contained in:
Sanjay Patel 2021-07-18 13:34:43 -04:00
parent c0f2c4ce10
commit fbe64f136f
1 changed files with 55 additions and 4 deletions
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59
llvm/test/Transforms/SimplifyCFG/fold-branch-to-common-dest.ll
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@ -121,10 +121,19 @@ final_right:
; FIXME: When we fold the dispatch block into pred, the call is moved to pred
; and the attribute nonnull is no longer valid on paramater. We should drop it.
define void @one_pred_with_spec_call(i8 %v0, i8 %v1, i32* %p) {
; CHECK-LABEL: one_pred_with_spec_call
; CHECK-LABEL: pred:
; CHECK: %c0 = icmp ne i32* %p, null
; CHECK: %x = call i32 @speculate_call(i32* nonnull %p)
; CHECK-LABEL: @one_pred_with_spec_call(
; CHECK-NEXT: pred:
; CHECK-NEXT: [[C0:%.*]] = icmp ne i32* [[P:%.*]], null
; CHECK-NEXT: [[X:%.*]] = call i32 @speculate_call(i32* nonnull [[P]])
; CHECK-NEXT: [[C1:%.*]] = icmp eq i8 [[V1:%.*]], 0
; CHECK-NEXT: [[OR_COND:%.*]] = select i1 [[C0]], i1 [[C1]], i1 false
; CHECK-NEXT: br i1 [[OR_COND]], label [[COMMON_RET:%.*]], label [[FINAL_RIGHT:%.*]]
; CHECK: common.ret:
; CHECK-NEXT: ret void
; CHECK: final_right:
; CHECK-NEXT: call void @sideeffect0()
; CHECK-NEXT: br label [[COMMON_RET]]
;
pred:
%c0 = icmp ne i32* %p, null
br i1 %c0, label %dispatch, label %final_right
@ -988,4 +997,46 @@ for.end:
ret void
}
; FIXME:
; This is a miscompile if we replace a phi incoming value
; with an updated loaded value *after* it was stored.
@global_pr51125 = global i32 1, align 4
define i32 @pr51125() {
; CHECK-LABEL: @pr51125(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[LD_OLD:%.*]] = load i32, i32* @global_pr51125, align 4
; CHECK-NEXT: [[ISZERO_OLD:%.*]] = icmp eq i32 [[LD_OLD]], 0
; CHECK-NEXT: br i1 [[ISZERO_OLD]], label [[EXIT:%.*]], label [[L2:%.*]]
; CHECK: L2:
; CHECK-NEXT: [[LD_MERGE:%.*]] = phi i32 [ [[LD:%.*]], [[L2]] ], [ [[LD_OLD]], [[ENTRY:%.*]] ]
; CHECK-NEXT: store i32 -1, i32* @global_pr51125, align 4
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[LD_MERGE]], -1
; CHECK-NEXT: [[LD]] = load i32, i32* @global_pr51125, align 4
; CHECK-NEXT: [[ISZERO:%.*]] = icmp eq i32 [[LD]], 0
; CHECK-NEXT: [[OR_COND:%.*]] = select i1 [[CMP]], i1 true, i1 [[ISZERO]]
; CHECK-NEXT: br i1 [[OR_COND]], label [[EXIT]], label [[L2]]
; CHECK: exit:
; CHECK-NEXT: [[R:%.*]] = phi i32 [ [[LD]], [[L2]] ], [ [[LD_OLD]], [[ENTRY]] ]
; CHECK-NEXT: ret i32 [[R]]
;
entry:
br label %L
L:
%ld = load i32, i32* @global_pr51125, align 4
%iszero = icmp eq i32 %ld, 0
br i1 %iszero, label %exit, label %L2
L2:
store i32 -1, i32* @global_pr51125, align 4
%cmp = icmp eq i32 %ld, -1
br i1 %cmp, label %L, label %exit
exit:
%r = phi i32 [ %ld, %L2 ], [ %ld, %L ]
ret i32 %r
}
attributes #0 = { nounwind argmemonly speculatable }