From 01236e3eca6b7fba347fb6b88c6fdcd7624d45ad Mon Sep 17 00:00:00 2001 From: Andrea Di Biagio Date: Fri, 12 Dec 2014 12:41:22 +0000 Subject: [PATCH] [MachineScheduler] Fix for PR21807: minor code difference building with/without -g. This patch fixes the issue reported as PR21807. There was a minor difference in the generated code depending on the -g flag. The cause was that with -g the machine scheduler used a different scheduling strategy. This decision was based on the number of instructions in a schedule region and included debug instructions in that count. This patch fixes the issue in MISched and provides a test. Patch by Russell Gallop! llvm-svn: 224118 --- llvm/lib/CodeGen/MachineScheduler.cpp | 4 +- .../X86/misched-code-difference-with-debug.ll | 90 ++++++++++++++++++++++ 2 files changed, 93 insertions(+), 1 deletion(-) create mode 100644 llvm/test/CodeGen/X86/misched-code-difference-with-debug.ll diff --git a/llvm/lib/CodeGen/MachineScheduler.cpp b/llvm/lib/CodeGen/MachineScheduler.cpp index 261942f..cc8f3a0 100644 --- a/llvm/lib/CodeGen/MachineScheduler.cpp +++ b/llvm/lib/CodeGen/MachineScheduler.cpp @@ -430,9 +430,11 @@ void MachineSchedulerBase::scheduleRegions(ScheduleDAGInstrs &Scheduler) { // instruction stream until we find the nearest boundary. unsigned NumRegionInstrs = 0; MachineBasicBlock::iterator I = RegionEnd; - for(;I != MBB->begin(); --I, --RemainingInstrs, ++NumRegionInstrs) { + for(;I != MBB->begin(); --I, --RemainingInstrs) { if (isSchedBoundary(std::prev(I), MBB, MF, TII, IsPostRA)) break; + if (!I->isDebugValue()) + ++NumRegionInstrs; } // Notify the scheduler of the region, even if we may skip scheduling // it. Perhaps it still needs to be bundled. diff --git a/llvm/test/CodeGen/X86/misched-code-difference-with-debug.ll b/llvm/test/CodeGen/X86/misched-code-difference-with-debug.ll new file mode 100644 index 0000000..734a834 --- /dev/null +++ b/llvm/test/CodeGen/X86/misched-code-difference-with-debug.ll @@ -0,0 +1,90 @@ +; RUN: llc < %s -mcpu=generic | FileCheck %s +; Both functions should produce the same code. The presence of debug values +; should not affect the scheduling strategy. +; Generated from: +; char argc; +; class C { +; public: +; int test(char ,char ,char ,...); +; }; +; void foo() { +; C c; +; char lc = argc; +; c.test(0,argc,0,lc); +; c.test(0,argc,0,lc); +; } +; +; with +; clang -O2 -c test.cpp -emit-llvm -S +; clang -O2 -c test.cpp -emit-llvm -S -g +; + + +%class.C = type { i8 } + +@argc = global i8 0, align 1 + +declare i32 @test_function(%class.C*, i8 signext, i8 signext, i8 signext, ...) + +; CHECK-LABEL: test_without_debug +; CHECK: movl [[A:%[a-z]+]], [[B:%[a-z]+]] +; CHECK-NEXT: movl [[A]], [[C:%[a-z]+]] +define void @test_without_debug() { +entry: + %c = alloca %class.C, align 1 + %0 = load i8* @argc, align 1 + %conv = sext i8 %0 to i32 + %call = call i32 (%class.C*, i8, i8, i8, ...)* @test_function(%class.C* %c, i8 signext 0, i8 signext %0, i8 signext 0, i32 %conv) + %1 = load i8* @argc, align 1 + %call2 = call i32 (%class.C*, i8, i8, i8, ...)* @test_function(%class.C* %c, i8 signext 0, i8 signext %1, i8 signext 0, i32 %conv) + ret void +} + +; CHECK-LABEL: test_with_debug +; CHECK: movl [[A]], [[B]] +; CHECK-NEXT: movl [[A]], [[C]] +define void @test_with_debug() { +entry: + %c = alloca %class.C, align 1 + %0 = load i8* @argc, align 1 + tail call void @llvm.dbg.value(metadata !{i8 %0}, i64 0, metadata !19, metadata !29) + %conv = sext i8 %0 to i32 + tail call void @llvm.dbg.value(metadata !{%class.C* %c}, i64 0, metadata !18, metadata !29) + %call = call i32 (%class.C*, i8, i8, i8, ...)* @test_function(%class.C* %c, i8 signext 0, i8 signext %0, i8 signext 0, i32 %conv) + %1 = load i8* @argc, align 1 + call void @llvm.dbg.value(metadata !{%class.C* %c}, i64 0, metadata !18, metadata !29) + %call2 = call i32 (%class.C*, i8, i8, i8, ...)* @test_function(%class.C* %c, i8 signext 0, i8 signext %1, i8 signext 0, i32 %conv) + ret void +} + +declare void @llvm.dbg.value(metadata, i64, metadata, metadata) + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!22, !23} + +!0 = metadata !{metadata !"", metadata !1, metadata !2, metadata !3, metadata !12, metadata !20, metadata !2} ; [ DW_TAG_compile_unit ] [test.cpp] [DW_LANG_C_plus_plus] +!1 = metadata !{metadata !"test.cpp", metadata !""} +!2 = metadata !{} +!3 = metadata !{metadata !4} +!4 = metadata !{metadata !"0x2\00C\002\008\008\000\000\000", metadata !1, null, null, metadata !5, null, null, metadata !"_ZTS1C"} ; [ DW_TAG_class_type ] [C] [line 2, size 8, align 8, offset 0] [def] [from ] +!5 = metadata !{metadata !6} +!6 = metadata !{metadata !"", metadata !1, metadata !"_ZTS1C", metadata !7, null, null, null, null, null} ; [ DW_TAG_subprogram ] [line 4] [public] [test] +!7 = metadata !{metadata !"", null, null, null, metadata !8, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ] +!8 = metadata !{metadata !9, metadata !10, metadata !11, metadata !11, metadata !11, null} +!9 = metadata !{metadata !"", null, null} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed] +!10 = metadata !{metadata !"", null, null, metadata !"_ZTS1C"} ; [ DW_TAG_pointer_type ] [line 0, size 64, align 64, offset 0] [artificial] [from _ZTS1C] +!11 = metadata !{metadata !"0x24\00char\000\008\008\000\000\006", null, null} ; [ DW_TAG_base_type ] [char] [line 0, size 8, align 8, offset 0, enc DW_ATE_signed_char] +!12 = metadata !{metadata !13} +!13 = metadata !{metadata !"0x2e\00test_with_debug\00test_with_debug\00test_with_debug\006\000\001\000\000\00256\001\006", metadata !1, metadata !14, metadata !15, null, void ()* @test_with_debug, null, null, metadata !17} ; [ DW_TAG_subprogram ] [line 6] [def] [test_with_debug] +!14 = metadata !{metadata !"0x29", metadata !1} +!15 = metadata !{metadata !"0x15\00\000\000\000\000\000\000", null, null, null, metadata !16, null, null, null} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ] +!16 = metadata !{null} +!17 = metadata !{metadata !18, metadata !19} +!18 = metadata !{metadata !"0x100\00c\007\000", metadata !13, metadata !14, metadata !"_ZTS1C"} ; [ DW_TAG_auto_variable ] [c] [line 7] +!19 = metadata !{metadata !"0x100\00lc\008\000", metadata !13, metadata !14, metadata !11} ; [ DW_TAG_auto_variable ] [lc] [line 8] +!20 = metadata !{metadata !21} +!21 = metadata !{metadata !"0x34\00argc\00argc\00\001\000\001", null, metadata !14, metadata !11, i8* @argc, null} ; [ DW_TAG_variable ] [argc] [line 1] [def] +!22 = metadata !{i32 2, metadata !"Dwarf Version", i32 4} +!23 = metadata !{i32 2, metadata !"Debug Info Version", i32 2} +!25 = metadata !{i32 8, i32 3, metadata !13, null} +!29 = metadata !{metadata !"0x102"} ; [ DW_TAG_expression ] -- 2.7.4