llvm-6502/test/Transforms/LoopRotate/dbgvalue.ll
Chandler Carruth c0d18b6696 Fix ValueTracking to conclude that debug intrinsics are safe to
speculate. Without this, loop rotate (among many other places) would
suddenly stop working in the presence of debug info. I found this
looking at loop rotate, and have augmented its tests with a reduction
out of a very hot loop in yacr2 where failing to do this rotation costs
sometimes more than 10% in runtime performance, perturbing numerous
downstream optimizations.

This should have no impact on performance without debug info, but the
change in performance when debug info is enabled can be extreme. As
a consequence (and this how I got to this yak) any profiling of
performance problems should be treated with deep suspicion -- they may
have been wildly innacurate of debug info was enabled for profiling. =/
Just a heads up.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154263 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-07 19:22:18 +00:00

100 lines
4.8 KiB
LLVM

; RUN: opt -S -loop-rotate %s | FileCheck %s
declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
declare void @llvm.dbg.value(metadata, i64, metadata) nounwind readnone
define i32 @tak(i32 %x, i32 %y, i32 %z) nounwind ssp {
; CHECK: define i32 @tak
; CHECK: entry
; CHECK-NEXT: call void @llvm.dbg.value(metadata !{i32 %x}
entry:
br label %tailrecurse
tailrecurse: ; preds = %if.then, %entry
%x.tr = phi i32 [ %x, %entry ], [ %call, %if.then ]
%y.tr = phi i32 [ %y, %entry ], [ %call9, %if.then ]
%z.tr = phi i32 [ %z, %entry ], [ %call14, %if.then ]
tail call void @llvm.dbg.value(metadata !{i32 %x.tr}, i64 0, metadata !6), !dbg !7
tail call void @llvm.dbg.value(metadata !{i32 %y.tr}, i64 0, metadata !8), !dbg !9
tail call void @llvm.dbg.value(metadata !{i32 %z.tr}, i64 0, metadata !10), !dbg !11
%cmp = icmp slt i32 %y.tr, %x.tr, !dbg !12
br i1 %cmp, label %if.then, label %if.end, !dbg !12
if.then: ; preds = %tailrecurse
%sub = sub nsw i32 %x.tr, 1, !dbg !14
%call = tail call i32 @tak(i32 %sub, i32 %y.tr, i32 %z.tr), !dbg !14
%sub6 = sub nsw i32 %y.tr, 1, !dbg !14
%call9 = tail call i32 @tak(i32 %sub6, i32 %z.tr, i32 %x.tr), !dbg !14
%sub11 = sub nsw i32 %z.tr, 1, !dbg !14
%call14 = tail call i32 @tak(i32 %sub11, i32 %x.tr, i32 %y.tr), !dbg !14
br label %tailrecurse
if.end: ; preds = %tailrecurse
br label %return, !dbg !16
return: ; preds = %if.end
ret i32 %z.tr, !dbg !17
}
@channelColumns = external global i64
@horzPlane = external global i8*, align 8
define void @FindFreeHorzSeg(i64 %startCol, i64 %row, i64* %rowStart) {
; Ensure that the loop increment basic block is rotated into the tail of the
; body, even though it contains a debug intrinsic call.
; CHECK: define void @FindFreeHorzSeg
; CHECK: %dec = add
; CHECK-NEXT: tail call void @llvm.dbg.value
; CHECK-NEXT: br i1 %tobool, label %for.cond, label %for.end
entry:
br label %for.cond
for.cond:
%i.0 = phi i64 [ %startCol, %entry ], [ %dec, %for.inc ]
%cmp = icmp eq i64 %i.0, 0
br i1 %cmp, label %for.end, label %for.body
for.body:
%0 = load i64* @channelColumns, align 8
%mul = mul i64 %0, %row
%add = add i64 %mul, %i.0
%1 = load i8** @horzPlane, align 8
%arrayidx = getelementptr inbounds i8* %1, i64 %add
%2 = load i8* %arrayidx, align 1
%tobool = icmp eq i8 %2, 0
br i1 %tobool, label %for.inc, label %for.end
for.inc:
%dec = add i64 %i.0, -1
tail call void @llvm.dbg.value(metadata !{i64 %dec}, i64 0, metadata undef)
br label %for.cond
for.end:
%add1 = add i64 %i.0, 1
store i64 %add1, i64* %rowStart, align 8
ret void
}
!llvm.dbg.sp = !{!0}
!0 = metadata !{i32 589870, i32 0, metadata !1, metadata !"tak", metadata !"tak", metadata !"", metadata !1, i32 32, metadata !3, i1 false, i1 true, i32 0, i32 0, i32 0, i32 256, i1 false, i32 (i32, i32, i32)* @tak} ; [ DW_TAG_subprogram ]
!1 = metadata !{i32 589865, metadata !"/Volumes/Lalgate/cj/llvm/projects/llvm-test/SingleSource/Benchmarks/BenchmarkGame/recursive.c", metadata !"/Volumes/Lalgate/cj/D/projects/llvm-test/SingleSource/Benchmarks/BenchmarkGame", metadata !2} ; [ DW_TAG_file_type ]
!2 = metadata !{i32 589841, i32 0, i32 12, metadata !"/Volumes/Lalgate/cj/llvm/projects/llvm-test/SingleSource/Benchmarks/BenchmarkGame/recursive.c", metadata !"/Volumes/Lalgate/cj/D/projects/llvm-test/SingleSource/Benchmarks/BenchmarkGame", metadata !"clang version 2.9 (trunk 125492)", i1 true, i1 false, metadata !"", i32 0} ; [ DW_TAG_compile_unit ]
!3 = metadata !{i32 589845, metadata !1, metadata !"", metadata !1, i32 0, i64 0, i64 0, i32 0, i32 0, i32 0, metadata !4, i32 0, i32 0} ; [ DW_TAG_subroutine_type ]
!4 = metadata !{metadata !5}
!5 = metadata !{i32 589860, metadata !2, metadata !"int", null, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
!6 = metadata !{i32 590081, metadata !0, metadata !"x", metadata !1, i32 32, metadata !5, i32 0} ; [ DW_TAG_arg_variable ]
!7 = metadata !{i32 32, i32 13, metadata !0, null}
!8 = metadata !{i32 590081, metadata !0, metadata !"y", metadata !1, i32 32, metadata !5, i32 0} ; [ DW_TAG_arg_variable ]
!9 = metadata !{i32 32, i32 20, metadata !0, null}
!10 = metadata !{i32 590081, metadata !0, metadata !"z", metadata !1, i32 32, metadata !5, i32 0} ; [ DW_TAG_arg_variable ]
!11 = metadata !{i32 32, i32 27, metadata !0, null}
!12 = metadata !{i32 33, i32 3, metadata !13, null}
!13 = metadata !{i32 589835, metadata !0, i32 32, i32 30, metadata !1, i32 6} ; [ DW_TAG_lexical_block ]
!14 = metadata !{i32 34, i32 5, metadata !15, null}
!15 = metadata !{i32 589835, metadata !13, i32 33, i32 14, metadata !1, i32 7} ; [ DW_TAG_lexical_block ]
!16 = metadata !{i32 36, i32 3, metadata !13, null}
!17 = metadata !{i32 37, i32 1, metadata !13, null}