llvm-6502/test/CodeGen/X86/reverse_branches.ll
Manman Ren 1123614317 Reverse order of the two branches at end of a basic block if it is profitable.
We branch to the successor with higher edge weight first.
Convert from
     je    LBB4_8  --> to outer loop
     jmp   LBB4_14 --> to inner loop
to
     jne   LBB4_14
     jmp   LBB4_8

PR12750
rdar: 11393714


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161018 91177308-0d34-0410-b5e6-96231b3b80d8
2012-07-31 01:11:07 +00:00

105 lines
3.3 KiB
LLVM

; RUN: llc -mtriple=x86_64-apple-darwin < %s | FileCheck %s
@.str2 = private unnamed_addr constant [7 x i8] c"memchr\00", align 1
@.str3 = private unnamed_addr constant [11 x i8] c"bsd_memchr\00", align 1
@str4 = private unnamed_addr constant [5 x i8] c"Bug!\00"
; Make sure at end of do.cond.i, we jump to do.body.i first to have a tighter
; inner loop.
define i32 @test_branches_order() uwtable ssp {
; CHECK: test_branches_order:
; CHECK: [[L0:LBB0_[0-9]+]]: ## %do.body.i
; CHECK: je
; CHECK: %do.cond.i
; CHECK: jne [[L0]]
; CHECK: jmp
; CHECK: %exit
entry:
%strs = alloca [1000 x [1001 x i8]], align 16
br label %for.cond
for.cond:
%j.0 = phi i32 [ 0, %entry ], [ %inc10, %for.inc9 ]
%cmp = icmp slt i32 %j.0, 1000
br i1 %cmp, label %for.cond1, label %for.end11
for.cond1:
%indvars.iv50 = phi i64 [ %indvars.iv.next51, %for.body3 ], [ 0, %for.cond ]
%0 = trunc i64 %indvars.iv50 to i32
%cmp2 = icmp slt i32 %0, 1000
br i1 %cmp2, label %for.body3, label %for.inc9
for.body3:
%arraydecay = getelementptr inbounds [1000 x [1001 x i8]]* %strs, i64 0, i64 %indvars.iv50, i64 0
%call = call i8* @memchr(i8* %arraydecay, i32 120, i64 1000)
%add.ptr = getelementptr inbounds [1000 x [1001 x i8]]* %strs, i64 0, i64 %indvars.iv50, i64 %indvars.iv50
%cmp7 = icmp eq i8* %call, %add.ptr
%indvars.iv.next51 = add i64 %indvars.iv50, 1
br i1 %cmp7, label %for.cond1, label %if.then
if.then:
%puts = call i32 @puts(i8* getelementptr inbounds ([5 x i8]* @str4, i64 0, i64 0))
call void @exit(i32 1) noreturn
unreachable
for.inc9:
%inc10 = add nsw i32 %j.0, 1
br label %for.cond
for.end11:
%puts42 = call i32 @puts(i8* getelementptr inbounds ([7 x i8]* @.str2, i64 0, i64 0))
br label %for.cond14
for.cond14:
%j13.0 = phi i32 [ 0, %for.end11 ], [ %inc39, %for.inc38 ]
%cmp15 = icmp slt i32 %j13.0, 1000
br i1 %cmp15, label %for.cond18, label %for.end40
for.cond18:
%indvars.iv = phi i64 [ %indvars.iv.next, %exit ], [ 0, %for.cond14 ]
%1 = trunc i64 %indvars.iv to i32
%cmp19 = icmp slt i32 %1, 1000
br i1 %cmp19, label %for.body20, label %for.inc38
for.body20:
%arraydecay24 = getelementptr inbounds [1000 x [1001 x i8]]* %strs, i64 0, i64 %indvars.iv, i64 0
br label %do.body.i
do.body.i:
%n.addr.0.i = phi i64 [ %dec.i, %do.cond.i ], [ 1000, %for.body20 ]
%p.0.i = phi i8* [ %incdec.ptr.i, %do.cond.i ], [ %arraydecay24, %for.body20 ]
%2 = load i8* %p.0.i, align 1
%cmp3.i = icmp eq i8 %2, 120
br i1 %cmp3.i, label %exit, label %do.cond.i
do.cond.i:
%incdec.ptr.i = getelementptr inbounds i8* %p.0.i, i64 1
%dec.i = add i64 %n.addr.0.i, -1
%cmp5.i = icmp eq i64 %dec.i, 0
br i1 %cmp5.i, label %if.then32, label %do.body.i
exit:
%add.ptr30 = getelementptr inbounds [1000 x [1001 x i8]]* %strs, i64 0, i64 %indvars.iv, i64 %indvars.iv
%cmp31 = icmp eq i8* %p.0.i, %add.ptr30
%indvars.iv.next = add i64 %indvars.iv, 1
br i1 %cmp31, label %for.cond18, label %if.then32
if.then32:
%puts43 = call i32 @puts(i8* getelementptr inbounds ([5 x i8]* @str4, i64 0, i64 0))
call void @exit(i32 1) noreturn
unreachable
for.inc38:
%inc39 = add nsw i32 %j13.0, 1
br label %for.cond14
for.end40:
%puts44 = call i32 @puts(i8* getelementptr inbounds ([11 x i8]* @.str3, i64 0, i64 0))
ret i32 0
}
declare i8* @memchr(i8*, i32, i64) nounwind readonly
declare void @exit(i32) noreturn
declare i32 @puts(i8* nocapture) nounwind