From 8ecde6cbf87cfa3184cec5a4eedb70b06dbb4a85 Mon Sep 17 00:00:00 2001 From: Eli Friedman Date: Thu, 27 Oct 2011 01:33:51 +0000 Subject: [PATCH] It is not safe to sink an alloca into a stacksave/stackrestore pair, so don't do that. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143093 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/IndVarSimplify.cpp | 11 ++--- test/Transforms/IndVarSimplify/sink-alloca.ll | 43 +++++++++++++++---- 2 files changed, 40 insertions(+), 14 deletions(-) diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp index 75fa011a14b..874a135110d 100644 --- a/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -1680,11 +1680,12 @@ void IndVarSimplify::SinkUnusedInvariants(Loop *L) { if (isa(I)) continue; - // Don't sink static AllocaInsts out of the entry block, which would - // turn them into dynamic allocas! - if (AllocaInst *AI = dyn_cast(I)) - if (AI->isStaticAlloca()) - continue; + // Don't sink alloca: we never want to sink static alloca's out of the + // entry block, and correctly sinking dynamic alloca's requires + // checks for stacksave/stackrestore intrinsics. + // FIXME: Refactor this check somehow? + if (isa(I)) + continue; // Determine if there is a use in or before the loop (direct or // otherwise). diff --git a/test/Transforms/IndVarSimplify/sink-alloca.ll b/test/Transforms/IndVarSimplify/sink-alloca.ll index 3a6c683e7ce..e7d642c9b31 100644 --- a/test/Transforms/IndVarSimplify/sink-alloca.ll +++ b/test/Transforms/IndVarSimplify/sink-alloca.ll @@ -1,15 +1,10 @@ ; RUN: opt < %s -indvars -S | FileCheck %s -; PR4775 - -; Indvars shouldn't sink the alloca out of the entry block, even though -; it's not used until after the loop. - target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128" target triple = "i386-apple-darwin10.0" -@llvm.used = appending global [1 x i8*] [i8* bitcast (i32 ()* @main to i8*)], -section "llvm.metadata" ; <[1 x i8*]*> [#uses=0] - +; PR4775 +; Indvars shouldn't sink the alloca out of the entry block, even though +; it's not used until after the loop. define i32 @main() nounwind { ; CHECK: entry: ; CHECK-NEXT: %result.i = alloca i32, align 4 @@ -27,5 +22,35 @@ while.end: ; preds = %while.cond %tmp.i = volatile load i32* %result.i ; [#uses=0] ret i32 0 } - declare i32 @bar() + +; +; Indvars shouldn't sink the first alloca between the stacksave and stackrestore +; intrinsics. +declare i8* @a(...) +declare i8* @llvm.stacksave() nounwind +declare void @llvm.stackrestore(i8*) nounwind +define void @h(i64 %n) nounwind uwtable ssp { +; CHECK: entry: +; CHECK-NEXT: %vla = alloca i8* +; CHECK-NEXT: %savedstack = call i8* @llvm.stacksave() +entry: + %vla = alloca i8*, i64 %n, align 16 + %savedstack = call i8* @llvm.stacksave() nounwind + %vla.i = alloca i8*, i64 %n, align 16 + br label %for.body.i + +for.body.i: + %indvars.iv37.i = phi i64 [ %indvars.iv.next38.i, %for.body.i ], [ 0, %entry ] + %call.i = call i8* (...)* @a() nounwind + %arrayidx.i = getelementptr inbounds i8** %vla.i, i64 %indvars.iv37.i + store i8* %call.i, i8** %arrayidx.i, align 8 + %indvars.iv.next38.i = add i64 %indvars.iv37.i, 1 + %exitcond5 = icmp eq i64 %indvars.iv.next38.i, %n + br i1 %exitcond5, label %g.exit, label %for.body.i + +g.exit: + call void @llvm.stackrestore(i8* %savedstack) nounwind + %call1 = call i8* (...)* @a(i8** %vla) nounwind + ret void +} -- 2.34.1