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llvm-mirror/test/Transforms/SimplifyCFG/pr48778-sdiv-speculation.ll
Roman Lebedev a7fa6b8e79 [NFCI-ish][SimplifyCFGPass] Rework and generalize ret block tail-merging
This changes the approach taken to tail-merge the blocks
to always create a new block instead of trying to reuse some block,
and generalizes it to support dealing not with just the `ret` in the future.

This effectively lifts the CallBr restriction, although this isn't really intentional.
That is the only non-NFC change here, i'm not sure if it's reasonable/feasible to temporarily retain it.

Other restrictions of the transform remain.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D104598
2021-06-23 14:33:18 +03:00

30 lines
894 B
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -simplifycfg -S < %s | FileCheck %s
; sdiv INT_MIN / -1 should not be speculated.
define i32 @test(i1 %cmp) {
; CHECK-LABEL: @test(
; CHECK-NEXT: br i1 [[CMP:%.*]], label [[IF:%.*]], label [[COMMON_RET:%.*]]
; CHECK: if:
; CHECK-NEXT: [[DIV:%.*]] = sdiv i32 -2147483648, -1
; CHECK-NEXT: [[CMP2:%.*]] = icmp ne i32 [[DIV]], 0
; CHECK-NEXT: [[SPEC_SELECT:%.*]] = select i1 [[CMP2]], i32 1, i32 0
; CHECK-NEXT: br label [[COMMON_RET]]
; CHECK: common.ret:
; CHECK-NEXT: [[COMMON_RET_OP:%.*]] = phi i32 [ 0, [[TMP0:%.*]] ], [ [[SPEC_SELECT]], [[IF]] ]
; CHECK-NEXT: ret i32 [[COMMON_RET_OP]]
;
br i1 %cmp, label %if, label %else
if:
%div = sdiv i32 -2147483648, -1
%cmp2 = icmp ne i32 %div, 0
br i1 %cmp2, label %end, label %else
else:
ret i32 0
end:
ret i32 1
}