a1532ed275
Change `CountersPtr` in `__profd_` to a label difference, which is a link-time
constant. On ELF, when linking a shared object, this requires that `__profc_` is
either private or linkonce/linkonce_odr hidden. On COFF, we need D104564 so that
`.quad a-b` (64-bit label difference) can lower to a 32-bit PC-relative relocation.
```
# ELF: R_X86_64_PC64 (PC-relative)
.quad .L__profc_foo-.L__profd_foo
# Mach-O: a pair of 8-byte X86_64_RELOC_UNSIGNED and X86_64_RELOC_SUBTRACTOR
.quad l___profc_foo-l___profd_foo
# COFF: we actually use IMAGE_REL_AMD64_REL32/IMAGE_REL_ARM64_REL32 so
# the high 32-bit value is zero even if .L__profc_foo < .L__profd_foo
# As compensation, we truncate CountersDelta in the header so that
# __llvm_profile_merge_from_buffer and llvm-profdata reader keep working.
.quad .L__profc_foo-.L__profd_foo
```
(Note: link.exe sorts `.lprfc` before `.lprfd` even if the object writer
has `.lprfd` before `.lprfc`, so we cannot work around by reordering
`.lprfc` and `.lprfd`.)
With this change, a stage 2 (`-DLLVM_TARGETS_TO_BUILD=X86 -DLLVM_BUILD_INSTRUMENTED=IR`)
`ld -pie` linked clang is 1.74% smaller due to fewer R_X86_64_RELATIVE relocations.
```
% readelf -r pie | awk '$3~/R.*/{s[$3]++} END {for (k in s) print k, s[k]}'
R_X86_64_JUMP_SLO 331
R_X86_64_TPOFF64 2
R_X86_64_RELATIVE 476059 # was: 607712
R_X86_64_64 2616
R_X86_64_GLOB_DAT 31
```
The absolute function address (used by llvm-profdata to collect indirect call
targets) can be converted to relative as well, but is not done in this patch.
Differential Revision: https://reviews.llvm.org/D104556
101 lines
4.5 KiB
LLVM
101 lines
4.5 KiB
LLVM
; RUN: opt < %s -pgo-instr-gen -S | FileCheck %s --check-prefix=GEN
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; RUN: opt < %s -passes=pgo-instr-gen -S | FileCheck %s --check-prefix=GEN
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; RUN: opt < %s -passes=pgo-instr-gen,instrprof -vp-static-alloc=true -S | FileCheck %s --check-prefix=LOWER
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; RUN: opt < %s -passes=pgo-instr-gen,instrprof -vp-static-alloc=false -S | FileCheck %s --check-prefix=LOWER
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target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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$novp_inline = comdat any
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$vp_inline = comdat any
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@bar = external global void ()*, align 8
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; GEN: @__profn_novp_inline = linkonce_odr hidden constant [11 x i8] c"novp_inline"
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; GEN: @__profn_foo = private constant [3 x i8] c"foo"
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; GEN: @__profn_vp_inline = linkonce_odr hidden constant [9 x i8] c"vp_inline"
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;; Test that a linkonce function's address is recorded.
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;; We allow a linkonce profd to be private if the function does not use value profiling.
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; LOWER: @__profd_novp_inline.[[HASH:[0-9]+]] = private global {{.*}} @__profc_novp_inline.[[HASH]]
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; LOWER-SAME: i8* bitcast (void ()* @novp_inline to i8*)
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; LOWER: @__profd_foo = private {{.*}} @__profc_foo
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;; __profd_vp_inline.[[#]] is referenced by code and may be referenced by other
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;; text sections due to inlining. It can't be local because a linker error would
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;; occur if a prevailing text section references the non-prevailing local symbol.
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; LOWER: @__profd_vp_inline.[[FOO_HASH:[0-9]+]] = linkonce_odr hidden {{.*}} @__profc_vp_inline.[[FOO_HASH]]
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; LOWER-SAME: i8* bitcast (void ()* @vp_inline to i8*)
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define linkonce_odr void @novp_inline() comdat {
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ret void
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}
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define void @foo() {
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entry:
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; GEN: @foo()
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; GEN: entry:
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; GEN-NEXT: call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 [[#FOO_HASH:]], i32 1, i32 0)
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%tmp = load void ()*, void ()** @bar, align 8
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; GEN: [[ICALL_TARGET:%[0-9]+]] = ptrtoint void ()* %tmp to i64
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; GEN-NEXT: call void @llvm.instrprof.value.profile(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 [[#FOO_HASH]], i64 [[ICALL_TARGET]], i32 0, i32 0)
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; LOWER: call void @__llvm_profile_instrument_target(i64 %1, i8* bitcast ({ i64, i64, i64, i8*, i8*, i32, [2 x i16] }* @__profd_foo to i8*), i32 0)
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call void %tmp()
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ret void
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}
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define linkonce_odr void @vp_inline() comdat {
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entry:
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; GEN: @vp_inline()
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; GEN: entry:
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; GEN-NEXT: call void @llvm.instrprof.increment(i8* getelementptr inbounds ([9 x i8], [9 x i8]* @__profn_vp_inline, i32 0, i32 0), i64 [[#FOO_HASH:]], i32 1, i32 0)
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%tmp = load void ()*, void ()** @bar, align 8
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; GEN: [[ICALL_TARGET:%[0-9]+]] = ptrtoint void ()* %tmp to i64
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; GEN-NEXT: call void @llvm.instrprof.value.profile(i8* getelementptr inbounds ([9 x i8], [9 x i8]* @__profn_vp_inline, i32 0, i32 0), i64 [[#FOO_HASH]], i64 [[ICALL_TARGET]], i32 0, i32 0)
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; LOWER: call void @__llvm_profile_instrument_target(i64 %1, i8* bitcast ({ i64, i64, i64, i8*, i8*, i32, [2 x i16] }* @__profd_vp_inline.[[#]] to i8*), i32 0)
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call void %tmp()
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ret void
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}
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@bar2 = global void ()* null, align 8
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@_ZTIi = external constant i8*
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define i32 @foo2(i32 %arg, i8** nocapture readnone %arg1) personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
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bb:
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%tmp2 = load void ()*, void ()** @bar2, align 8
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invoke void %tmp2()
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to label %bb10 unwind label %bb2
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; GEN: [[ICALL_TARGET2:%[0-9]+]] = ptrtoint void ()* %tmp2 to i64
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; GEN-NEXT: call void @llvm.instrprof.value.profile(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @__profn_foo2, i32 0, i32 0), i64 [[FOO2_HASH:[0-9]+]], i64 [[ICALL_TARGET2]], i32 0, i32 0)
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bb2: ; preds = %bb
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%tmp3 = landingpad { i8*, i32 }
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catch i8* bitcast (i8** @_ZTIi to i8*)
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%tmp4 = extractvalue { i8*, i32 } %tmp3, 1
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%tmp5 = tail call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
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%tmp6 = icmp eq i32 %tmp4, %tmp5
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br i1 %tmp6, label %bb7, label %bb11
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bb7: ; preds = %bb2
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%tmp8 = extractvalue { i8*, i32 } %tmp3, 0
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%tmp9 = tail call i8* @__cxa_begin_catch(i8* %tmp8)
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tail call void @__cxa_end_catch()
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br label %bb10
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bb10: ; preds = %bb7, %bb
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ret i32 0
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bb11: ; preds = %bb2
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resume { i8*, i32 } %tmp3
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}
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declare i32 @__gxx_personality_v0(...)
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; Function Attrs: nounwind readnone
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declare i32 @llvm.eh.typeid.for(i8*) #0
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declare i8* @__cxa_begin_catch(i8*)
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declare void @__cxa_end_catch()
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