From 75b51621540c23ddfc1e9ef6b4dc803453d9d122 Mon Sep 17 00:00:00 2001 From: Benjamin Kramer Date: Tue, 25 Jun 2013 13:34:40 +0000 Subject: [PATCH] BlockFrequency: Bump up the entry frequency a bit. This is a band-aid to fix the most severe regressions we're seeing from basing spill decisions on block frequencies, until we have a better solution. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184835 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/BlockFrequencyImpl.h | 2 +- include/llvm/Analysis/BlockFrequencyInfo.h | 8 +++--- include/llvm/Support/BlockFrequency.h | 2 +- lib/Analysis/BlockFrequencyInfo.cpp | 5 ---- lib/CodeGen/MachineBlockFrequencyInfo.cpp | 5 ---- test/Analysis/BlockFrequencyInfo/basic.ll | 32 +++++++++++----------- 6 files changed, 22 insertions(+), 32 deletions(-) diff --git a/include/llvm/Analysis/BlockFrequencyImpl.h b/include/llvm/Analysis/BlockFrequencyImpl.h index b3e2d18eb2c..d555e0ef4c9 100644 --- a/include/llvm/Analysis/BlockFrequencyImpl.h +++ b/include/llvm/Analysis/BlockFrequencyImpl.h @@ -33,7 +33,7 @@ class BlockFrequencyInfo; class MachineBlockFrequencyInfo; /// BlockFrequencyImpl implements block frequency algorithm for IR and -/// Machine Instructions. Algorithm starts with value 1024 (START_FREQ) +/// Machine Instructions. Algorithm starts with value ENTRY_FREQ /// for the entry block and then propagates frequencies using branch weights /// from (Machine)BranchProbabilityInfo. LoopInfo is not required because /// algorithm can find "backedges" by itself. diff --git a/include/llvm/Analysis/BlockFrequencyInfo.h b/include/llvm/Analysis/BlockFrequencyInfo.h index fcab90677a4..267e43b5d9c 100644 --- a/include/llvm/Analysis/BlockFrequencyInfo.h +++ b/include/llvm/Analysis/BlockFrequencyInfo.h @@ -43,10 +43,10 @@ public: void print(raw_ostream &O, const Module *M) const; /// getblockFreq - Return block frequency. Return 0 if we don't have the - /// information. Please note that initial frequency is equal to 1024. It means - /// that we should not rely on the value itself, but only on the comparison to - /// the other block frequencies. We do this to avoid using of floating points. - /// + /// information. Please note that initial frequency is equal to ENTRY_FREQ. It + /// means that we should not rely on the value itself, but only on the + /// comparison to the other block frequencies. We do this to avoid using of + /// floating points. BlockFrequency getBlockFreq(const BasicBlock *BB) const; }; diff --git a/include/llvm/Support/BlockFrequency.h b/include/llvm/Support/BlockFrequency.h index 77b1bf44138..85e9437a571 100644 --- a/include/llvm/Support/BlockFrequency.h +++ b/include/llvm/Support/BlockFrequency.h @@ -25,7 +25,7 @@ class BranchProbability; class BlockFrequency { uint64_t Frequency; - static const int64_t ENTRY_FREQ = 1024; + static const int64_t ENTRY_FREQ = 1 << 14; public: BlockFrequency(uint64_t Freq = 0) : Frequency(Freq) { } diff --git a/lib/Analysis/BlockFrequencyInfo.cpp b/lib/Analysis/BlockFrequencyInfo.cpp index 100e5c8ae7d..8469556f64c 100644 --- a/lib/Analysis/BlockFrequencyInfo.cpp +++ b/lib/Analysis/BlockFrequencyInfo.cpp @@ -53,11 +53,6 @@ void BlockFrequencyInfo::print(raw_ostream &O, const Module *) const { if (BFI) BFI->print(O); } -/// getblockFreq - Return block frequency. Return 0 if we don't have the -/// information. Please note that initial frequency is equal to 1024. It means -/// that we should not rely on the value itself, but only on the comparison to -/// the other block frequencies. We do this to avoid using of floating points. -/// BlockFrequency BlockFrequencyInfo::getBlockFreq(const BasicBlock *BB) const { return BFI->getBlockFreq(BB); } diff --git a/lib/CodeGen/MachineBlockFrequencyInfo.cpp b/lib/CodeGen/MachineBlockFrequencyInfo.cpp index 070daf2e2ba..e269d24e1d5 100644 --- a/lib/CodeGen/MachineBlockFrequencyInfo.cpp +++ b/lib/CodeGen/MachineBlockFrequencyInfo.cpp @@ -50,11 +50,6 @@ bool MachineBlockFrequencyInfo::runOnMachineFunction(MachineFunction &F) { return false; } -/// getblockFreq - Return block frequency. Return 0 if we don't have the -/// information. Please note that initial frequency is equal to 1024. It means -/// that we should not rely on the value itself, but only on the comparison to -/// the other block frequencies. We do this to avoid using of floating points. -/// BlockFrequency MachineBlockFrequencyInfo:: getBlockFreq(const MachineBasicBlock *MBB) const { return MBFI->getBlockFreq(MBB); diff --git a/test/Analysis/BlockFrequencyInfo/basic.ll b/test/Analysis/BlockFrequencyInfo/basic.ll index 540d06b1f56..a9be431b709 100644 --- a/test/Analysis/BlockFrequencyInfo/basic.ll +++ b/test/Analysis/BlockFrequencyInfo/basic.ll @@ -2,12 +2,12 @@ define i32 @test1(i32 %i, i32* %a) { ; CHECK: Printing analysis {{.*}} for function 'test1' -; CHECK: entry = 1024 +; CHECK: entry = 16384 entry: br label %body ; Loop backedges are weighted and thus their bodies have a greater frequency. -; CHECK: body = 31744 +; CHECK: body = 524288 body: %iv = phi i32 [ 0, %entry ], [ %next, %body ] %base = phi i32 [ 0, %entry ], [ %sum, %body ] @@ -18,29 +18,29 @@ body: %exitcond = icmp eq i32 %next, %i br i1 %exitcond, label %exit, label %body -; CHECK: exit = 1024 +; CHECK: exit = 16384 exit: ret i32 %sum } define i32 @test2(i32 %i, i32 %a, i32 %b) { ; CHECK: Printing analysis {{.*}} for function 'test2' -; CHECK: entry = 1024 +; CHECK: entry = 16384 entry: %cond = icmp ult i32 %i, 42 br i1 %cond, label %then, label %else, !prof !0 ; The 'then' branch is predicted more likely via branch weight metadata. -; CHECK: then = 963 +; CHECK: then = 15420 then: br label %exit -; CHECK: else = 60 +; CHECK: else = 963 else: br label %exit -; FIXME: It may be a bug that we don't sum back to 1024. -; CHECK: exit = 1023 +; FIXME: It may be a bug that we don't sum back to 16384. +; CHECK: exit = 16383 exit: %result = phi i32 [ %a, %then ], [ %b, %else ] ret i32 %result @@ -50,36 +50,36 @@ exit: define i32 @test3(i32 %i, i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) { ; CHECK: Printing analysis {{.*}} for function 'test3' -; CHECK: entry = 1024 +; CHECK: entry = 16384 entry: switch i32 %i, label %case_a [ i32 1, label %case_b i32 2, label %case_c i32 3, label %case_d i32 4, label %case_e ], !prof !1 -; CHECK: case_a = 51 +; CHECK: case_a = 819 case_a: br label %exit -; CHECK: case_b = 51 +; CHECK: case_b = 819 case_b: br label %exit ; The 'case_c' branch is predicted more likely via branch weight metadata. -; CHECK: case_c = 819 +; CHECK: case_c = 13107 case_c: br label %exit -; CHECK: case_d = 51 +; CHECK: case_d = 819 case_d: br label %exit -; CHECK: case_e = 51 +; CHECK: case_e = 819 case_e: br label %exit -; FIXME: It may be a bug that we don't sum back to 1024. -; CHECK: exit = 1023 +; FIXME: It may be a bug that we don't sum back to 16384. +; CHECK: exit = 16383 exit: %result = phi i32 [ %a, %case_a ], [ %b, %case_b ],