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Codegen: Fix broken assumption in Tail Merge.

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Tail merge was making the assumption that a layout successor or
predecessor was always a cfg successor/predecessor. Remove that
assumption. Changes to tests are necessary because the errant cfg edges
were preventing optimizations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273700 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kyle Butt 2016-06-24 18:16:36 +00:00
parent d4e43baeb0
commit 546c8eba34
7 changed files with 45 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
lib/CodeGen/BranchFolding.cpp
View File

@ -1255,7 +1255,7 @@ ReoptimizeBlock:
// where a BB jumps to more than one landing pad.
// TODO: Is it ever worth rewriting predecessors which don't already
// jump to a landing pad, and so can safely jump to the fallthrough?
} else {
} else if (MBB->isSuccessor(&*FallThrough)) {
// Rewrite all predecessors of the old block to go to the fallthrough
// instead.
while (!MBB->pred_empty()) {

2
test/CodeGen/Mips/eh.ll
View File

@ -24,7 +24,7 @@ entry:
lpad: ; preds = %entry
; CHECK-EL: # %lpad
; CHECK-EL: beq $5
; CHECK-EL: bne $5
%exn.val = landingpad { i8*, i32 }
cleanup

4
test/CodeGen/SPARC/missinglabel.ll
View File

@ -4,14 +4,14 @@ target triple = "sparc64-unknown-linux-gnu"
define void @f() align 2 {
entry:
; CHECK: %xcc, .LBB0_1
; CHECK: %xcc, .LBB0_2
%cmp = icmp eq i64 undef, 0
br i1 %cmp, label %targetblock, label %cond.false
cond.false:
unreachable
; CHECK: .LBB0_1: ! %targetblock
; CHECK: .LBB0_2: ! %targetblock
targetblock:
br i1 undef, label %cond.false.i83, label %exit.i85

4
test/CodeGen/Thumb2/thumb2-cbnz.ll
View File

@ -5,6 +5,7 @@ declare double @foo(double) nounwind readnone
define void @t(i32 %c, double %b) {
entry:
; CHECK: cmp r0, #0
%cmp1 = icmp ne i32 %c, 0
br i1 %cmp1, label %bb3, label %bb1
@ -23,8 +24,7 @@ bb7: ; preds = %bb3
br i1 %cmp3, label %bb11, label %bb9
bb9: ; preds = %bb7
; CHECK: cmp r0, #0
; CHECK-NEXT: cbnz
; CHECK: cbnz
%0 = tail call double @foo(double %b) nounwind readnone ; <double> [#uses=0]
br label %bb11

25
test/CodeGen/Thumb2/v8_IT_5.ll
View File

@ -17,31 +17,13 @@
define i32 @t(i32 %type) optsize {
entry:
br i1 undef, label %if.then, label %if.else
if.then:
unreachable
if.else:
br i1 undef, label %if.then15, label %if.else18
if.then15:
unreachable
if.else18:
switch i32 %type, label %if.else173 [
i32 3, label %if.then115
i32 1, label %if.then102
i32 13, label %if.then115
i32 6, label %if.then102
]
if.then102:
br i1 undef, label %cond.true10.i, label %t.exit
cond.true10.i:
br label %t.exit
t.exit:
unreachable
br label %if.then115
if.then115:
br i1 undef, label %if.else163, label %if.else145
@ -62,4 +44,3 @@ if.else173:
}
declare hidden fastcc %struct.hc* @foo(%struct.hc* nocapture, i32) nounwind optsize

2
test/CodeGen/X86/br-fold.ll
View File

@ -5,9 +5,11 @@
; RUN: llc -mtriple=x86_64-scei-ps4 < %s | FileCheck -check-prefix=PS4 %s
; X64_DARWIN: orq
; X64_DARWIN-NEXT: jne
; X64_DARWIN-NEXT: %bb8.i329
; X64_LINUX: orq %rax, %rcx
; X64_LINUX-NEXT: jne
; X64_LINUX-NEXT: %bb8.i329
; X64_WINDOWS: orq %rax, %rcx

34
test/CodeGen/X86/tail-merge-unreachable.ll Normal file
View File

@ -0,0 +1,34 @@
; RUN: llc -mtriple=x86_64-linux-gnu %s -o - -verify-machineinstrs | FileCheck %s
define i32 @tail_merge_unreachable(i32 %i) {
entry:
br i1 undef, label %sw, label %end
sw:
switch i32 %i, label %end [
i32 99, label %sw.bb
i32 98, label %sw.bb
i32 101, label %sw.bb
i32 97, label %sw.bb2
i32 96, label %sw.bb2
i32 100, label %sw.bb2
]
sw.bb:
unreachable
sw.bb2:
unreachable
end:
%p = phi i32 [ 1, %sw ], [ 0, %entry ]
ret i32 %p
; CHECK-LABEL: tail_merge_unreachable:
; Range Check
; CHECK: addl $-96
; CHECK: cmpl $5
; CHECK: jbe [[JUMP_TABLE_BLOCK:[.][A-Za-z0-9_]+]]
; CHECK: retq
; CHECK: [[JUMP_TABLE_BLOCK]]:
; CHECK: btl
; CHECK: jae [[UNREACHABLE_BLOCK:[.][A-Za-z0-9_]+]]
; CHECK [[UNREACHABLE_BLOCK]]:
; CHECK: .Lfunc_end0
}