From 831687d1576efd003b20c0574831bdf2ce317e60 Mon Sep 17 00:00:00 2001 From: Michael Zolotukhin Date: Tue, 22 Sep 2015 21:41:29 +0000 Subject: [PATCH] [Unroll] Follow-up for r247769: fix a bug in UnrolledInstAnalyzer::visitLoad. Apart from checking that GlobalVariable is a constant, we should check that it's not a weak constant, in which case we can't propagate its value. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248327 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/LoopUnrollPass.cpp | 2 +- .../LoopUnroll/full-unroll-heuristics-2.ll | 32 +++++++++++++++++-- 2 files changed, 31 insertions(+), 3 deletions(-) diff --git a/lib/Transforms/Scalar/LoopUnrollPass.cpp b/lib/Transforms/Scalar/LoopUnrollPass.cpp index 0e4462618aa..d9236a2c773 100644 --- a/lib/Transforms/Scalar/LoopUnrollPass.cpp +++ b/lib/Transforms/Scalar/LoopUnrollPass.cpp @@ -415,7 +415,7 @@ private: auto *GV = dyn_cast(AddressIt->second.Base); // We're only interested in loads that can be completely folded to a // constant. - if (!GV || !GV->hasInitializer() || !GV->isConstant()) + if (!GV || !GV->hasDefinitiveInitializer() || !GV->isConstant()) return false; ConstantDataSequential *CDS = diff --git a/test/Transforms/LoopUnroll/full-unroll-heuristics-2.ll b/test/Transforms/LoopUnroll/full-unroll-heuristics-2.ll index cd687834fdf..5df48e8c380 100644 --- a/test/Transforms/LoopUnroll/full-unroll-heuristics-2.ll +++ b/test/Transforms/LoopUnroll/full-unroll-heuristics-2.ll @@ -1,11 +1,13 @@ ; RUN: opt < %s -S -loop-unroll -unroll-max-iteration-count-to-analyze=1000 -unroll-threshold=10 -unroll-percent-dynamic-cost-saved-threshold=50 -unroll-dynamic-cost-savings-discount=90 | FileCheck %s target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" +@unknown_global = internal unnamed_addr global [9 x i32] [i32 0, i32 -1, i32 0, i32 -1, i32 5, i32 -1, i32 0, i32 -1, i32 0], align 16 +@weak_constant = weak unnamed_addr constant [9 x i32] [i32 0, i32 -1, i32 0, i32 -1, i32 5, i32 -1, i32 0, i32 -1, i32 0], align 16 + ; Though @unknown_global is initialized with constant values, we can't consider ; it as a constant, so we shouldn't unroll the loop. +; CHECK-LABEL: @foo ; CHECK: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @unknown_global, i64 0, i64 %iv -@unknown_global = internal unnamed_addr global [9 x i32] [i32 0, i32 -1, i32 0, i32 -1, i32 5, i32 -1, i32 0, i32 -1, i32 0], align 16 - define i32 @foo(i32* noalias nocapture readonly %src) { entry: br label %loop @@ -27,3 +29,29 @@ loop.end: ; preds = %loop %r.lcssa = phi i32 [ %r, %loop ] ret i32 %r.lcssa } + +; Similarly, we can't consider 'weak' symbols as a known constant value, so we +; shouldn't unroll the loop. +; CHECK-LABEL: @foo2 +; CHECK: %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @weak_constant, i64 0, i64 %iv +define i32 @foo2(i32* noalias nocapture readonly %src) { +entry: + br label %loop + +loop: ; preds = %loop, %entry + %iv = phi i64 [ 0, %entry ], [ %inc, %loop ] + %r = phi i32 [ 0, %entry ], [ %add, %loop ] + %arrayidx = getelementptr inbounds i32, i32* %src, i64 %iv + %src_element = load i32, i32* %arrayidx, align 4 + %array_const_idx = getelementptr inbounds [9 x i32], [9 x i32]* @weak_constant, i64 0, i64 %iv + %const_array_element = load i32, i32* %array_const_idx, align 4 + %mul = mul nsw i32 %src_element, %const_array_element + %add = add nsw i32 %mul, %r + %inc = add nuw nsw i64 %iv, 1 + %exitcond86.i = icmp eq i64 %inc, 9 + br i1 %exitcond86.i, label %loop.end, label %loop + +loop.end: ; preds = %loop + %r.lcssa = phi i32 [ %r, %loop ] + ret i32 %r.lcssa +} -- 2.34.1