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James Y Knight 582ae3d23e Correctly modify the CFG in IfConverter, and then remove the
CorrectExtraCFGEdges function.

The latter was a workaround for "Various pieces of code" leaving bogus
extra CFG edges in place. Where by "various" it meant only
IfConverter::MergeBlocks, which failed to clear all of the successors
of dead blocks it emptied out. This wouldn't matter a whole lot,
except that the dead blocks remained listed as predecessors of
still-useful blocks, inhibiting optimizations.

This fix slightly changed two thumb tests, because the correct CFG
successors allowed for the "diamond" if-conversion pattern to be
detected, when it could only use "simple" before.

Additionally, the removal of a now-redundant call to analyzeBranch
(with AllowModify=true) in BranchFolder::OptimizeFunction caused a
later check for an empty block in BranchFolder::OptimizeBlock to
fail. Correct this by moving the call to analyzeBranch in
OptimizeBlock higher.

Differential Revision: https://reviews.llvm.org/D79527
2020-05-07 18:17:07 -04:00

34 lines
749 B
LLVM

; RUN: llc -mtriple=arm-eabi -mcpu=cortex-a8 %s -o - | FileCheck %s
; RUN: llc -mtriple=arm-eabi -mattr=+v4t %s -o - | FileCheck %s -check-prefix CHECK-V4-CMP
; RUN: llc -mtriple=arm-eabi -mattr=+v4t %s -o - | FileCheck %s -check-prefix CHECK-V4-BX
define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) {
; CHECK-LABEL: t1:
; CHECK: cmp r2, #7
; CHECK: cmpne r2, #1
switch i32 %c, label %cond_next [
i32 1, label %cond_true
i32 7, label %cond_true
]
cond_true:
; CHECK: addne r0
; CHECK: addeq r0
; CHECK: addeq r0
; CHECK: bx
%tmp12 = add i32 %a, 1
%tmp1518 = add i32 %tmp12, %b
ret i32 %tmp1518
cond_next:
%tmp15 = add i32 %b, %a
ret i32 %tmp15
}
; CHECK-V4-CMP: cmpne
; CHECK-V4-CMP-NOT: cmpne
; CHECK-V4-BX: bx
; CHECK-V4-BX-NOT: bx