[llvm] r311604 - [PGO] Set edge weights for indirectbr instruction with profile counts

[Rong Xu via llvm-commits]

Author: xur
Date: Wed Aug 23 14:36:02 2017
New Revision: 311604

URL: http://llvm.org/viewvc/llvm-project?rev=311604&view=rev
Log:
[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

Added:
    llvm/trunk/test/Transforms/PGOProfile/Inputs/indirectbr.proftext
    llvm/trunk/test/Transforms/PGOProfile/indirectbr.ll
Modified:
    llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
    llvm/trunk/lib/Transforms/Instrumentation/PGOInstrumentation.cpp

Modified: llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp?rev=311604&r1=311603&r2=311604&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp Wed Aug 23 14:36:02 2017
@@ -237,7 +237,7 @@ bool BranchProbabilityInfo::calcUnreacha
 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);

Modified: llvm/trunk/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/PGOInstrumentation.cpp?rev=311604&r1=311603&r2=311604&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/PGOInstrumentation.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/PGOInstrumentation.cpp Wed Aug 23 14:36:02 2017
@@ -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;

Added: llvm/trunk/test/Transforms/PGOProfile/Inputs/indirectbr.proftext
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/PGOProfile/Inputs/indirectbr.proftext?rev=311604&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/PGOProfile/Inputs/indirectbr.proftext (added)
+++ llvm/trunk/test/Transforms/PGOProfile/Inputs/indirectbr.proftext Wed Aug 23 14:36:02 2017
@@ -0,0 +1,13 @@
+# IR level Instrumentation Flag
+:ir
+foo
+# Func Hash:
+40197883220
+# Num Counters:
+4
+# Counter Values:
+202
+88
+20
+5
+

Added: llvm/trunk/test/Transforms/PGOProfile/indirectbr.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/PGOProfile/indirectbr.ll?rev=311604&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/PGOProfile/indirectbr.ll (added)
+++ llvm/trunk/test/Transforms/PGOProfile/indirectbr.ll Wed Aug 23 14:36:02 2017
@@ -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"
+
+ at 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]
+
+
+