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[PGO] Set edge weights for indirectbr instruction with profile counts 

Current PGO only annotates the edge weight for branch and switch instructions
with profile counts. We should also annotate the indirectbr instruction as
all the information is there. This patch enables the annotating for indirectbr
instructions. Also uses this annotation in branch probability analysis.

Differential Revision: https://reviews.llvm.org/D37074

llvm-svn: 311604
This commit is contained in:
Rong Xu 2017-08-23 21:36:02 +00:00
parent 8040a215c9
commit 15848e5977
4 changed files with 64 additions and 2 deletions
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2
llvm/lib/Analysis/BranchProbabilityInfo.cpp
View File

@ -237,7 +237,7 @@ bool BranchProbabilityInfo::calcUnreachableHeuristics(const BasicBlock *BB) {
bool BranchProbabilityInfo::calcMetadataWeights(const BasicBlock *BB) {
const TerminatorInst *TI = BB->getTerminator();
assert(TI->getNumSuccessors() > 1 && "expected more than one successor!");
if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
if (!(isa<BranchInst>(TI) || isa<SwitchInst>(TI) || isa<IndirectBrInst>(TI)))
return false;
MDNode *WeightsNode = TI->getMetadata(LLVMContext::MD_prof);

3
llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
View File

@ -1094,7 +1094,8 @@ void PGOUseFunc::setBranchWeights() {
TerminatorInst *TI = BB.getTerminator();
if (TI->getNumSuccessors() < 2)
continue;
if (!isa<BranchInst>(TI) && !isa<SwitchInst>(TI))
if (!(isa<BranchInst>(TI) || isa<SwitchInst>(TI) ||
isa<IndirectBrInst>(TI)))
continue;
if (getBBInfo(&BB).CountValue == 0)
continue;

13
llvm/test/Transforms/PGOProfile/Inputs/indirectbr.proftext Normal file
View File

@ -0,0 +1,13 @@
# IR level Instrumentation Flag
:ir
foo
# Func Hash:
40197883220
# Num Counters:
4
# Counter Values:
202
88
20
5

48
llvm/test/Transforms/PGOProfile/indirectbr.ll Normal file
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@ -0,0 +1,48 @@
; RUN: llvm-profdata merge %S/Inputs/indirectbr.proftext -o %t.profdata
; RUN: opt < %s -pgo-instr-use -pgo-test-profile-file=%t.profdata -S | FileCheck %s --check-prefix=USE
; New PM
; RUN: opt < %s -passes=pgo-instr-use -pgo-test-profile-file=%t.profdata -S | FileCheck %s --check-prefix=USE
; RUN: opt < %s -passes=pgo-instr-use -pgo-test-profile-file=%t.profdata -S | opt -S -analyze -branch-prob | FileCheck %s --check-prefix=BRANCHPROB
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
@foo.table = internal unnamed_addr constant [3 x i8*] [i8* blockaddress(@foo, %return), i8* blockaddress(@foo, %label2), i8* blockaddress(@foo, %label3)], align 16
define i32 @foo(i32 %i) {
entry:
%cmp = icmp ult i32 %i, 3
br i1 %cmp, label %if.then, label %return
if.then:
%idxprom = zext i32 %i to i64
%arrayidx = getelementptr inbounds [3 x i8*], [3 x i8*]* @foo.table, i64 0, i64 %idxprom
%0 = load i8*, i8** %arrayidx, align 8
indirectbr i8* %0, [label %return, label %label2, label %label3]
; USE: indirectbr i8* %0, [label %return, label %label2, label %label3]
; USE-SAME: !prof ![[BW_INDBR:[0-9]+]]
; USE: ![[BW_INDBR]] = !{!"branch_weights", i32 63, i32 20, i32 5}
label2:
br label %return
label3:
br label %return
return:
%retval.0 = phi i32 [ 3, %label3 ], [ 2, %label2 ], [ 0, %entry ], [ 1, %if.then ]
ret i32 %retval.0
}
; BRANCHPROB: Printing analysis 'Branch Probability Analysis' for function 'foo':
; BRANCHPROB:---- Branch Probabilities ----
; BRANCHPROB: edge entry -> if.then probability is 0x37c32b17 / 0x80000000 = 43.56%
; BRANCHPROB: edge entry -> return probability is 0x483cd4e9 / 0x80000000 = 56.44%
; BRANCHPROB: edge if.then -> return probability is 0x5ba2e8ba / 0x80000000 = 71.59%
; BRANCHPROB: edge if.then -> label2 probability is 0x1d1745d1 / 0x80000000 = 22.73%
; BRANCHPROB: edge if.then -> label3 probability is 0x0745d174 / 0x80000000 = 5.68%
; BRANCHPROB: edge label2 -> return probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
; BRANCHPROB: edge label3 -> return probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]