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[ThinLTO] Indirect call promotion fixes for promoted local functions

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Summary:
Fix a couple issues limiting the application of indirect call promotion
in ThinLTO mode:
- Invoke indirect call promotion before globalopt, since it may
  eliminate imported functions which appear unreferenced.
- Invoke indirect call promotion with InLTO=true so that the PGOFuncName
  metadata is used to get the name for locals which would have been
  renamed during promotion.

Reviewers: davidxl, mehdi_amini

Subscribers: Prazek, llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D24004

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280024 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Teresa Johnson 2016-08-29 22:46:56 +00:00
parent e060ffb4b2
commit cf538716fb
4 changed files with 36 additions and 6 deletions
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3
lib/ProfileData/InstrProf.cpp
View File

@ -136,6 +136,9 @@ std::string getPGOFuncName(StringRef RawFuncName,
// (when \c InLTO is true): LTO's internalization privatizes many global linkage
// symbols. This happens after value profile annotation, but those internal
// linkage functions should not have a source prefix.
// Additionally, for ThinLTO mode, exported internal functions are promoted
// and renamed. We need to ensure that the original internal PGO name is
// used when computing the GUID that is compared against the profiled GUIDs.
// To differentiate compiler generated internal symbols from original ones,
// PGOFuncName meta data are created and attached to the original internal
// symbols in the value profile annotation step

17
lib/Transforms/IPO/PassManagerBuilder.cpp
View File

@ -405,6 +405,16 @@ void PassManagerBuilder::populateModulePassManager(
addInitialAliasAnalysisPasses(MPM);
// For ThinLTO there are two passes of indirect call promotion. The
// first is during the compile phase when PerformThinLTO=false and
// intra-module indirect call targets are promoted. The second is during
// the ThinLTO backend when PerformThinLTO=true, when we promote imported
// inter-module indirect calls. For that we perform indirect call promotion
// earlier in the pass pipeline, here before globalopt. Otherwise imported
// available_externally functions look unreferenced and are removed.
if (PerformThinLTO)
MPM.add(createPGOIndirectCallPromotionLegacyPass(/*InLTO = */ true));
if (!DisableUnitAtATime) {
// Infer attributes about declarations if possible.
MPM.add(createInferFunctionAttrsLegacyPass());
@ -427,11 +437,12 @@ void PassManagerBuilder::populateModulePassManager(
/// PGO instrumentation is added during the compile phase for ThinLTO, do
/// not run it a second time
addPGOInstrPasses(MPM);
// Indirect call promotion that promotes intra-module targets only.
// For ThinLTO this is done earlier due to interactions with globalopt
// for imported functions.
MPM.add(createPGOIndirectCallPromotionLegacyPass());
}
// Indirect call promotion that promotes intra-module targets only.
MPM.add(createPGOIndirectCallPromotionLegacyPass());
if (EnableNonLTOGlobalsModRef)
// We add a module alias analysis pass here. In part due to bugs in the
// analysis infrastructure this "works" in that the analysis stays alive

9
test/Transforms/PGOProfile/Inputs/thinlto_indirect_call_promotion.ll
View File

@ -1,7 +1,16 @@
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
source_filename = "thinlto_indirect_call_promotion.c"
define void @a() {
entry:
ret void
}
define internal void @c() !PGOFuncName !1 {
entry:
ret void
}
!1 = !{!"thinlto_indirect_call_promotion.c:c"}

13
test/Transforms/PGOProfile/thinlto_indirect_call_promotion.ll
View File

@ -4,26 +4,33 @@
; RUN: llvm-lto -thinlto -o %t3 %t.bc %t2.bc
; RUN: opt -function-import -summary-file %t3.thinlto.bc %t.bc -o %t4.bc -print-imports 2>&1 | FileCheck %s --check-prefix=IMPORTS
; IMPORTS: Import a
; IMPORTS-DAG: Import a
; IMPORTS-DAG: Import c
; RUN: opt %t4.bc -pgo-icall-prom -S -icp-count-threshold=1 | FileCheck %s --check-prefix=ICALL-PROM
; RUN: opt %t4.bc -pgo-icall-prom -S -pass-remarks=pgo-icall-prom -icp-count-threshold=1 2>&1 | FileCheck %s --check-prefix=PASS-REMARK
; RUN: opt %t4.bc -icp-lto -pgo-icall-prom -S -icp-count-threshold=1 | FileCheck %s --check-prefix=ICALL-PROM
; RUN: opt %t4.bc -icp-lto -pgo-icall-prom -S -pass-remarks=pgo-icall-prom -icp-count-threshold=1 2>&1 | FileCheck %s --check-prefix=PASS-REMARK
; PASS-REMARK: Promote indirect call to a with count 1 out of 1
; PASS-REMARK: Promote indirect call to c.llvm.0 with count 1 out of 1
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
@foo = external local_unnamed_addr global void ()*, align 8
@bar = external local_unnamed_addr global void ()*, align 8
define i32 @main() local_unnamed_addr {
entry:
%0 = load void ()*, void ()** @foo, align 8
; ICALL-PROM: br i1 %{{[0-9]+}}, label %if.true.direct_targ, label %if.false.orig_indirect, !prof [[BRANCH_WEIGHT:![0-9]+]]
tail call void %0(), !prof !1
%1 = load void ()*, void ()** @bar, align 8
; ICALL-PROM: br i1 %{{[0-9]+}}, label %if.true.direct_targ1, label %if.false.orig_indirect2, !prof [[BRANCH_WEIGHT:![0-9]+]]
tail call void %1(), !prof !2
ret i32 0
}
!1 = !{!"VP", i32 0, i64 1, i64 -6289574019528802036, i64 1}
!2 = !{!"VP", i32 0, i64 1, i64 591260329866125152, i64 1}
; Should not have a VP annotation on new indirect call (check before and after
; branch_weights annotation).