From 51177295c485abc6b7967a385ab85b274f3878a2 Mon Sep 17 00:00:00 2001 From: Teresa Johnson Date: Fri, 28 Apr 2017 14:30:54 +0000 Subject: [PATCH] Memory intrinsic value profile optimization: Avoid divide by 0 Summary: Skip memops if the total value profiled count is 0, we can't correctly scale up the counts and there is no point anyway. Reviewers: davidxl Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D32624 llvm-svn: 301645 --- .../Instrumentation/IndirectCallPromotion.cpp | 4 ++++ .../PGOProfile/memop_size_opt_zero.ll | 19 +++++++++++++++++++ 2 files changed, 23 insertions(+) create mode 100644 llvm/test/Transforms/PGOProfile/memop_size_opt_zero.ll diff --git a/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp b/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp index 75fb2d40653f..493d014586c6 100644 --- a/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp +++ b/llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp @@ -872,6 +872,10 @@ bool MemOPSizeOpt::perform(MemIntrinsic *MI) { if (ActualCount < MemOPCountThreshold) return false; + // Skip if the total value profiled count is 0, in which case we can't + // scale up the counts properly (and there is no profitable transformation). + if (TotalCount == 0) + return false; TotalCount = ActualCount; if (MemOPScaleCount) diff --git a/llvm/test/Transforms/PGOProfile/memop_size_opt_zero.ll b/llvm/test/Transforms/PGOProfile/memop_size_opt_zero.ll new file mode 100644 index 000000000000..ede34f0de803 --- /dev/null +++ b/llvm/test/Transforms/PGOProfile/memop_size_opt_zero.ll @@ -0,0 +1,19 @@ +; Test to ensure the pgo memop optimization pass doesn't try to scale +; up a value profile with a 0 count, which would lead to divide by 0. +; RUN: opt < %s -passes=pgo-memop-opt -pgo-memop-count-threshold=1 -S | FileCheck %s --check-prefix=MEMOP_OPT +; RUN: opt < %s -pgo-memop-opt -pgo-memop-count-threshold=1 -S | FileCheck %s --check-prefix=MEMOP_OPT + +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +define void @foo(i8* %dst, i8* %src, i64 %conv) !prof !0 { + call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %conv, i32 1, i1 false), !prof !1 + ret void +} + +; MEMOP_OPT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* %dst, i8* %src, i64 %conv, i32 1, i1 false), !prof !1 + +!0 = !{!"function_entry_count", i64 1} +!1 = !{!"VP", i32 1, i64 0, i64 1, i64 0, i64 2, i64 0, i64 3, i64 0, i64 9, i64 0, i64 4, i64 0, i64 5, i64 0, i64 6, i64 0, i64 7, i64 0, i64 8, i64 0} + +declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture writeonly, i8* nocapture readonly, i64, i32, i1)