This is an archive of the discontinued LLVM Phabricator instance.

Differential D22089

Do not rewrite fputs to fwrite when optimising for size
ClosedPublic

Authored by SjoerdMeijer on Jul 7 2016, 5:54 AM.

Download Raw Diff

Details

Reviewers

ab
jmolloy
beanz

Summary

Code size optimisation: don't rewrite fputs to fwrite when optimising for size because fwrite requires more arguments and thus extra MOVs are required.

Diff Detail

Event Timeline

SjoerdMeijer updated this revision to Diff 63061.Jul 7 2016, 5:54 AM

SjoerdMeijer retitled this revision from to Do not rewrite fputs to fwrite when optimising for size.

SjoerdMeijer updated this object.

SjoerdMeijer added reviewers: ab, beanz, jmolloy.

SjoerdMeijer added a subscriber: llvm-commits.

Hi Sjoerd,

This LGTM.

Cheers,

James

This revision is now accepted and ready to land.Jul 7 2016, 6:47 AM

Committed revision 274753

Revision Contents

Path

Size

lib/

Transforms/

Utils/

SimplifyLibCalls.cpp

2 lines

test/

Transforms/

InstCombine/

fputs-opt-size.ll

28 lines

Diff 63061

lib/Transforms/Utils/SimplifyLibCalls.cpp

Show First 20 Lines • Show All 2,050 Lines • ▼ Show 20 Lines	case LibFunc::printf:
return optimizePrintF(CI, Builder);		return optimizePrintF(CI, Builder);
case LibFunc::sprintf:		case LibFunc::sprintf:
return optimizeSPrintF(CI, Builder);		return optimizeSPrintF(CI, Builder);
case LibFunc::fprintf:		case LibFunc::fprintf:
return optimizeFPrintF(CI, Builder);		return optimizeFPrintF(CI, Builder);
case LibFunc::fwrite:		case LibFunc::fwrite:
return optimizeFWrite(CI, Builder);		return optimizeFWrite(CI, Builder);
case LibFunc::fputs:		case LibFunc::fputs:
		if (CI->getParent()->getParent()->optForSize())
		return nullptr;
return optimizeFPuts(CI, Builder);		return optimizeFPuts(CI, Builder);
case LibFunc::log:		case LibFunc::log:
case LibFunc::log10:		case LibFunc::log10:
case LibFunc::log1p:		case LibFunc::log1p:
case LibFunc::log2:		case LibFunc::log2:
case LibFunc::logb:		case LibFunc::logb:
return optimizeLog(CI, Builder);		return optimizeLog(CI, Builder);
case LibFunc::puts:		case LibFunc::puts:
▲ Show 20 Lines • Show All 278 Lines • Show Last 20 Lines

test/Transforms/InstCombine/fputs-opt-size.ll

This file was added.

				; When optimising for size, we don't want to rewrite fputs to fwrite
				; because it requires more arguments and thus extra MOVs are required.
				;
				; RUN: opt < %s -instcombine -S \| FileCheck %s

				%struct._IO_FILE = type { i32, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, %struct._IO_marker, %struct._IO_FILE, i32, i32, i32, i16, i8, [1 x i8], i8, i64, i8, i8, i8, i8, i32, i32, [40 x i8] }
				%struct._IO_marker = type { %struct._IO_marker, %struct._IO_FILE, i32 }

				@.str = private unnamed_addr constant [10 x i8] c"mylog.txt\00", align 1
				@.str.1 = private unnamed_addr constant [2 x i8] c"a\00", align 1
				@.str.2 = private unnamed_addr constant [27 x i8] c"Hello world this is a test\00", align 1

				define i32 @main() local_unnamed_addr #0 {
				entry:
				; CHECK-LABEL: @main(
				; CHECK-NOT: call i64 @fwrite
				; CHECK: call i32 @fputs

				%call = tail call %struct._IO_FILE* @fopen(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str, i32 0, i32 0), i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.1, i32 0, i32 0)) #2
				%call1 = tail call i32 @fputs(i8* getelementptr inbounds ([27 x i8], [27 x i8]* @.str.2, i32 0, i32 0), %struct._IO_FILE* %call) #2
				ret i32 0
				}

				declare noalias %struct._IO_FILE* @fopen(i8* nocapture readonly, i8* nocapture readonly) local_unnamed_addr #1
				declare i32 @fputs(i8* nocapture readonly, %struct._IO_FILE* nocapture) local_unnamed_addr #1

				attributes #0 = { nounwind optsize }
				attributes #1 = { nounwind optsize }