8b2aba2e20
This patch implements the speculative devirtualization feature in the LLVM backend. It handles the case of single implementation devirtualization where there is a single possible callee of a virtual function. - Add cl::opt 'devirtualize-speculatively' to enable it. - Flag is disabled by default. - It works regardless of the visibility of the object. - Not enabled for LTO for now.
133 lines
5.4 KiB
LLVM
133 lines
5.4 KiB
LLVM
; -stats requires asserts
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; REQUIRES: asserts
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; Check that we can still devirtualize outside LTO mode when speculative devirtualization is enabled.
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; Check that we skip devirtualization for empty functions in speculative devirtualization mode
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; RUN: opt -S -passes=wholeprogramdevirt -devirtualize-speculatively \
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; RUN: -pass-remarks=wholeprogramdevirt -stats %s 2>&1 | FileCheck %s
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target datalayout = "e-p:64:64"
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target triple = "x86_64-unknown-linux-gnu"
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; CHECK: remark: devirt-single.cc:30:32: single-impl: devirtualized a call to vf
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; CHECK: remark: devirt-single.cc:41:32: single-impl: devirtualized a call to vf
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; CHECK: remark: devirt-single.cc:51:32: single-impl: devirtualized a call to vf
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; CHECK: remark: devirt-single.cc:13:0: devirtualized vf
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; CHECK-NOT: devirtualized
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@vt1 = constant [1 x ptr] [ptr @vf], !type !8
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@vt2 = constant [1 x ptr] [ptr @vf_empty], !type !12
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define i1 @vf(ptr %this) #0 !dbg !7 {
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ret i1 true
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}
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; This should NOT be devirtualized because during non-lto empty functions
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; are skipped.
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define void @vf_empty(ptr %this) !dbg !11 {
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ret void
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}
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; CHECK: define void @call
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define void @call(ptr %obj) #1 !dbg !5 {
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%vtable = load ptr, ptr %obj
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%p = call i1 @llvm.public.type.test(ptr %vtable, metadata !"typeid")
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call void @llvm.assume(i1 %p)
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%fptr = load ptr, ptr %vtable
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; CHECK: if.true.direct_targ:
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; CHECK: call i1 @vf(
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; CHECK: if.false.orig_indirect:
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; CHECK: call i1 %fptr(
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call i1 %fptr(ptr %obj), !dbg !6
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ret void
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}
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; CHECK: define void @call1
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define void @call1(ptr %obj) #1 !dbg !9 {
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%vtable = load ptr, ptr %obj
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%p = call i1 @llvm.type.test(ptr %vtable, metadata !"typeid1")
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call void @llvm.assume(i1 %p)
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%fptr = load ptr, ptr %vtable, align 8
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; CHECK: call i1 %fptr
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%1 = call i1 %fptr(ptr %obj), !dbg !10
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ret void
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}
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declare ptr @llvm.load.relative.i32(ptr, i32)
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@vt3 = private unnamed_addr constant [1 x i32] [
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i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @vf to i64), i64 ptrtoint (ptr @vt3 to i64)) to i32)
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], align 4, !type !15
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; CHECK: define void @call2
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define void @call2(ptr %obj) #1 !dbg !13 {
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%vtable = load ptr, ptr %obj
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%p = call i1 @llvm.type.test(ptr %vtable, metadata !"typeid2")
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call void @llvm.assume(i1 %p)
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%fptr = call ptr @llvm.load.relative.i32(ptr %vtable, i32 0)
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; CHECK: if.true.direct_targ:
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; CHECK: call i1 @vf(
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; CHECK: if.false.orig_indirect:
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; CHECK: call i1 %fptr(
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call i1 %fptr(ptr %obj), !dbg !14
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ret void
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}
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@_ZTV1A.local = private unnamed_addr constant { [3 x i32] } { [3 x i32] [
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i32 0, ; offset to top
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i32 0, ; rtti
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i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @vf to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [3 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 2) to i64)) to i32) ; vf_emptyunc offset
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] }, align 4, !type !18
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; CHECK: define void @call3
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define void @call3(ptr %obj) #1 !dbg !16 {
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%vtable = load ptr, ptr %obj
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%p = call i1 @llvm.type.test(ptr %vtable, metadata !"typeid3")
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call void @llvm.assume(i1 %p)
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%fptr = call ptr @llvm.load.relative.i32(ptr %vtable, i32 8)
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; CHECK: if.true.direct_targ:
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; CHECK: call i1 @vf(
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; CHECK: if.false.orig_indirect:
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; CHECK: call i1 %fptr(
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call i1 %fptr(ptr %obj), !dbg !17
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ret void
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}
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declare i1 @llvm.type.test(ptr, metadata)
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declare i1 @llvm.public.type.test(ptr, metadata)
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declare void @llvm.assume(i1)
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!2, !3}
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!llvm.ident = !{!4}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 4.0.0 (trunk 278098)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
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!1 = !DIFile(filename: "devirt-single.cc", directory: ".")
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!2 = !{i32 2, !"Dwarf Version", i32 4}
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!3 = !{i32 2, !"Debug Info Version", i32 3}
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!4 = !{!"clang version 4.0.0 (trunk 278098)"}
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!5 = distinct !DISubprogram(name: "call", linkageName: "_Z4callPv", scope: !1, file: !1, line: 29, isLocal: false, isDefinition: true, scopeLine: 9, flags: DIFlagPrototyped, isOptimized: false, unit: !0)
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!6 = !DILocation(line: 30, column: 32, scope: !5)
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!7 = distinct !DISubprogram(name: "vf", linkageName: "_ZN3vt12vfEv", scope: !1, file: !1, line: 13, isLocal: false, isDefinition: true, scopeLine: 13, flags: DIFlagPrototyped, isOptimized: false, unit: !0)
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!8 = !{i32 0, !"typeid"}
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!9 = distinct !DISubprogram(name: "call1", linkageName: "_Z5call1Pv", scope: !1, file: !1, line: 31, isLocal: false, isDefinition: true, scopeLine: 9, flags: DIFlagPrototyped, isOptimized: false, unit: !0)
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!10 = !DILocation(line: 35, column: 32, scope: !9)
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!11 = distinct !DISubprogram(name: "vf_empty", linkageName: "_ZN3vt18vf_emptyEv", scope: !1, file: !1, line: 23, isLocal: false, isDefinition: true, scopeLine: 23, flags: DIFlagPrototyped, isOptimized: false, unit: !0)
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!12 = !{i32 0, !"typeid1"}
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!13 = distinct !DISubprogram(name: "call2", linkageName: "_Z5call2Pv", scope: !1, file: !1, line: 40, isLocal: false, isDefinition: true, scopeLine: 9, flags: DIFlagPrototyped, isOptimized: false, unit: !0)
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!14 = !DILocation(line: 41, column: 32, scope: !13)
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!15 = !{i32 0, !"typeid2"}
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!16 = distinct !DISubprogram(name: "call3", linkageName: "_Z5call3Pv", scope: !1, file: !1, line: 50, isLocal: false, isDefinition: true, scopeLine: 9, flags: DIFlagPrototyped, isOptimized: false, unit: !0)
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!17 = !DILocation(line: 51, column: 32, scope: !16)
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!18 = !{i32 0, !"typeid3"}
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; CHECK: 1 wholeprogramdevirt - Number of whole program devirtualization targets
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; CHECK: 3 wholeprogramdevirt - Number of single implementation devirtualizations
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