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llvm-mirror/test/Transforms/SimplifyCFG/safe-abs.ll
Roman Lebedev 610e37f8c5 [SimplifyCFG] Teach FoldTwoEntryPHINode() to preserve DomTree
Still boring, simply drop all edges to successors of DomBlock,
and add an edge to to BB instead.
2020-12-20 00:18:33 +03:00

31 lines
1.1 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
; Reduced from arm_abs_q31() from CMSIS DSP suite.
; https://reviews.llvm.org/D65148#1629010
define i32 @abs_with_clamp(i32 %arg) {
; CHECK-LABEL: @abs_with_clamp(
; CHECK-NEXT: begin:
; CHECK-NEXT: [[IS_POSITIVE:%.*]] = icmp sgt i32 [[ARG:%.*]], 0
; CHECK-NEXT: [[IS_INT_MIN:%.*]] = icmp eq i32 [[ARG]], -2147483648
; CHECK-NEXT: [[NEGATED:%.*]] = sub nsw i32 0, [[ARG]]
; CHECK-NEXT: [[ABS:%.*]] = select i1 [[IS_INT_MIN]], i32 2147483647, i32 [[NEGATED]]
; CHECK-NEXT: [[TMP6:%.*]] = select i1 [[IS_POSITIVE]], i32 [[ARG]], i32 [[ABS]]
; CHECK-NEXT: ret i32 [[TMP6]]
;
begin:
%is_positive = icmp sgt i32 %arg, 0
br i1 %is_positive, label %end, label %negative
negative: ; preds = %begin
%is_int_min = icmp eq i32 %arg, -2147483648
%negated = sub nsw i32 0, %arg
%abs = select i1 %is_int_min, i32 2147483647, i32 %negated
br label %end
end: ; preds = %negative, %begin
%tmp6 = phi i32 [ %arg, %begin ], [ %abs, %negative ]
ret i32 %tmp6
}