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Change the basic block weight calculation algorithm to use max instead of voting. 

Summary: Now that we have more precise debug info, we should change back to use maximum to get basic block weight.

Reviewers: dnovillo

Subscribers: andreadb, llvm-commits

Differential Revision: https://reviews.llvm.org/D24788

llvm-svn: 282084
This commit is contained in:
Dehao Chen 2016-09-21 16:26:51 +00:00
parent a95e8bb7ed
commit 160fbc3f95
3 changed files with 14 additions and 22 deletions
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20
llvm/lib/Transforms/IPO/SampleProfile.cpp
View File

@ -513,24 +513,16 @@ SampleProfileLoader::getInstWeight(const Instruction &Inst) const {
/// \returns the weight for \p BB.
ErrorOr<uint64_t>
SampleProfileLoader::getBlockWeight(const BasicBlock *BB) const {
DenseMap<uint64_t, uint64_t> CM;
uint64_t Max = 0;
bool HasWeight = false;
for (auto &I : BB->getInstList()) {
const ErrorOr<uint64_t> &R = getInstWeight(I);
if (R)
CM[R.get()]++;
}
if (CM.size() == 0)
return std::error_code();
uint64_t W = 0, C = 0;
for (const auto &C_W : CM) {
if (C_W.second == W) {
C = std::max(C, C_W.first);
} else if (C_W.second > W) {
C = C_W.first;
W = C_W.second;
if (R) {
Max = std::max(Max, R.get());
HasWeight = true;
}
}
return C;
return HasWeight ? ErrorOr<uint64_t>(Max) : std::error_code();
}
/// \brief Compute and store the weights of every basic block.

8
llvm/test/Transforms/SampleProfile/calls.ll
View File

@ -48,8 +48,8 @@ while.cond: ; preds = %if.end, %entry
store i32 %inc, i32* %i, align 4, !dbg !14
%cmp = icmp slt i32 %0, 400000000, !dbg !14
br i1 %cmp, label %while.body, label %while.end, !dbg !14
; CHECK: edge while.cond -> while.body probability is 0x7ffa4e20 / 0x80000000 = 99.98% [HOT edge]
; CHECK: edge while.cond -> while.end probability is 0x0005b1e0 / 0x80000000 = 0.02%
; CHECK: edge while.cond -> while.body probability is 0x7d9eb367 / 0x80000000 = 98.14% [HOT edge]
; CHECK: edge while.cond -> while.end probability is 0x02614c99 / 0x80000000 = 1.86%
while.body: ; preds = %while.cond
%1 = load i32, i32* %i, align 4, !dbg !16
@ -59,8 +59,8 @@ while.body: ; preds = %while.cond
; both branches out of while.body had the same weight. In reality,
; the edge while.body->if.then is taken most of the time.
;
; CHECK: edge while.body -> if.else probability is 0x0005b1e0 / 0x80000000 = 0.02%
; CHECK: edge while.body -> if.then probability is 0x7ffa4e20 / 0x80000000 = 99.98% [HOT edge]
; CHECK: edge while.body -> if.else probability is 0x00059704 / 0x80000000 = 0.02%
; CHECK: edge while.body -> if.then probability is 0x7ffa68fc / 0x80000000 = 99.98% [HOT edge]
if.then: ; preds = %while.body

8
llvm/test/Transforms/SampleProfile/fnptr.ll
View File

@ -8,10 +8,10 @@
; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/fnptr.prof | opt -analyze -branch-prob | FileCheck %s
; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/fnptr.binprof | opt -analyze -branch-prob | FileCheck %s
; CHECK: edge for.body3 -> if.then probability is 0x1a56a56a / 0x80000000 = 20.58%
; CHECK: edge for.body3 -> if.else probability is 0x65a95a96 / 0x80000000 = 79.42%
; CHECK: edge for.inc -> for.inc12 probability is 0x000fdc50 / 0x80000000 = 0.05%
; CHECK: edge for.inc -> for.body3 probability is 0x7ff023b0 / 0x80000000 = 99.95%
; CHECK: edge for.body3 -> if.then probability is 0x19f584f3 / 0x80000000 = 20.28%
; CHECK: edge for.body3 -> if.else probability is 0x660a7b0d / 0x80000000 = 79.72%
; CHECK: edge for.inc -> for.inc12 probability is 0x000f92fb / 0x80000000 = 0.05%
; CHECK: edge for.inc -> for.body3 probability is 0x7ff06d05 / 0x80000000 = 99.95%
; CHECK: edge for.inc12 -> for.end14 probability is 0x04000000 / 0x80000000 = 3.12%
; CHECK: edge for.inc12 -> for.cond1.preheader probability is 0x7c000000 / 0x80000000 = 96.88%