From 0dee67560f17e43d32d52224c7f817226d75c646 Mon Sep 17 00:00:00 2001 From: "Duncan P. N. Exon Smith" Date: Tue, 17 Jun 2014 00:19:35 +0000 Subject: [PATCH] SROA: Only split loads on byte boundaries MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit r199771 accidently broke the logic that makes sure that SROA only splits load on byte boundaries. If such a split happens, some bits get lost when reassembling loads of wider types, causing data corruption. Move the width check up to reject such splits early, avoiding the corruption. Fixes PR19250. Patch by: Björn Steinbrink git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211082 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/SROA.cpp | 12 +++--- .../SROA/slice-order-independence.ll | 37 +++++++++++++++++++ test/Transforms/SROA/slice-width.ll | 25 +++++++++++++ 3 files changed, 69 insertions(+), 5 deletions(-) create mode 100644 test/Transforms/SROA/slice-order-independence.ll create mode 100644 test/Transforms/SROA/slice-width.ll diff --git a/lib/Transforms/Scalar/SROA.cpp b/lib/Transforms/Scalar/SROA.cpp index 04bf4f8dfc3..6532b7a09b9 100644 --- a/lib/Transforms/Scalar/SROA.cpp +++ b/lib/Transforms/Scalar/SROA.cpp @@ -1032,11 +1032,6 @@ static Type *findCommonType(AllocaSlices::const_iterator B, UserTy = SI->getValueOperand()->getType(); } - if (!UserTy || (Ty && Ty != UserTy)) - TyIsCommon = false; // Give up on anything but an iN type. - else - Ty = UserTy; - if (IntegerType *UserITy = dyn_cast_or_null(UserTy)) { // If the type is larger than the partition, skip it. We only encounter // this for split integer operations where we want to use the type of the @@ -1051,6 +1046,13 @@ static Type *findCommonType(AllocaSlices::const_iterator B, if (!ITy || ITy->getBitWidth() < UserITy->getBitWidth()) ITy = UserITy; } + + // To avoid depending on the order of slices, Ty and TyIsCommon must not + // depend on types skipped above. + if (!UserTy || (Ty && Ty != UserTy)) + TyIsCommon = false; // Give up on anything but an iN type. + else + Ty = UserTy; } return TyIsCommon ? Ty : ITy; diff --git a/test/Transforms/SROA/slice-order-independence.ll b/test/Transforms/SROA/slice-order-independence.ll new file mode 100644 index 00000000000..364ef85f1d1 --- /dev/null +++ b/test/Transforms/SROA/slice-order-independence.ll @@ -0,0 +1,37 @@ +; RUN: opt < %s -sroa -S | FileCheck %s +target datalayout = "e-p:64:64:64-p1:16:16:16-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n8:16:32:64" + +declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind + +; Check that the chosen type for a split is independent from the order of +; slices even in case of types that are skipped because their width is not a +; byte width multiple +define void @skipped_inttype_first({ i16*, i32 }*) { +; CHECK-LABEL: @skipped_inttype_first +; CHECK: alloca i8* + %arg = alloca { i16*, i32 }, align 8 + %2 = bitcast { i16*, i32 }* %0 to i8* + %3 = bitcast { i16*, i32 }* %arg to i8* + call void @llvm.memcpy.p0i8.p0i8.i32(i8* %3, i8* %2, i32 16, i32 8, i1 false) + %b = getelementptr inbounds { i16*, i32 }* %arg, i64 0, i32 0 + %pb0 = bitcast i16** %b to i63* + %b0 = load i63* %pb0 + %pb1 = bitcast i16** %b to i8** + %b1 = load i8** %pb1 + ret void +} + +define void @skipped_inttype_last({ i16*, i32 }*) { +; CHECK-LABEL: @skipped_inttype_last +; CHECK: alloca i8* + %arg = alloca { i16*, i32 }, align 8 + %2 = bitcast { i16*, i32 }* %0 to i8* + %3 = bitcast { i16*, i32 }* %arg to i8* + call void @llvm.memcpy.p0i8.p0i8.i32(i8* %3, i8* %2, i32 16, i32 8, i1 false) + %b = getelementptr inbounds { i16*, i32 }* %arg, i64 0, i32 0 + %pb1 = bitcast i16** %b to i8** + %b1 = load i8** %pb1 + %pb0 = bitcast i16** %b to i63* + %b0 = load i63* %pb0 + ret void +} diff --git a/test/Transforms/SROA/slice-width.ll b/test/Transforms/SROA/slice-width.ll new file mode 100644 index 00000000000..179780b4afe --- /dev/null +++ b/test/Transforms/SROA/slice-width.ll @@ -0,0 +1,25 @@ +; RUN: opt < %s -sroa -S | FileCheck %s +target datalayout = "e-p:64:64:64-p1:16:16:16-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-n8:16:32:64" + +declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind + +define void @no_split_on_non_byte_width(i32) { +; This tests that allocas are not split into slices that are not byte width multiple + %arg = alloca i32 , align 8 + store i32 %0, i32* %arg + br label %load_i32 + +load_i32: +; CHECK-LABEL: load_i32: +; CHECK-NOT: bitcast {{.*}} to i1 +; CHECK-NOT: zext i1 + %r0 = load i32* %arg + br label %load_i1 + +load_i1: +; CHECK-LABEL: load_i1: +; CHECK: bitcast {{.*}} to i1 + %p1 = bitcast i32* %arg to i1* + %t1 = load i1* %p1 + ret void +} -- 2.34.1