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Revert "Claim NoAlias if two GEPs index different fields of the same struct" 

This reverts commit 2d5d6493f43eb68493a3852b8c226ac9fafdc7eb.

llvm-svn: 271422
This commit is contained in:
Daniel Berlin 2016-06-01 18:55:32 +00:00
parent 18b83fe6cf
commit 73694bb92b
3 changed files with 172 additions and 238 deletions
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38
llvm/lib/Analysis/BasicAliasAnalysis.cpp
View File

@ -834,42 +834,8 @@ static AliasResult aliasSameBasePointerGEPs(const GEPOperator *GEP1,
// Try to determine whether GEP1 and GEP2 index through arrays, into structs,
// such that the struct field accesses provably cannot alias.
// We also need at least two indices (the pointer, and the struct field).
if (GEP1->getNumIndices() < 2)
return MayAlias;
// If both GEP1 and GEP2 have the inbounds keyword but index different fields
// of the same struct, they do not alias.
if (GEP1->isInBounds() && GEP2->isInBounds()) {
auto Opi1 = GEP1->op_begin() + 1;
auto Opi2 = GEP2->op_begin() + 1;
auto Ope1 = GEP1->op_end();
auto Ope2 = GEP2->op_end();
SmallVector<Value *, 8> IntermediateIndices;
ConstantInt *C1 = nullptr;
ConstantInt *C2 = nullptr;
while (Opi1 != Ope1 && Opi2 != Ope2 &&
(C1 = dyn_cast<ConstantInt>(*Opi1)) &&
(C2 = dyn_cast<ConstantInt>(*Opi2))) {
if (C1 == C2) {
IntermediateIndices.push_back(C1);
++Opi1;
++Opi2;
} else {
// Both GEPs share the same pointer operand and access through the same
// indices up to this point, but now they are having different index
// values. At this point, if the indexed type is a StructType, this means
// that two GEPs are for two different fields in the same structure.
auto *Ty = GetElementPtrInst::getIndexedType(
GEP1->getSourceElementType(), IntermediateIndices);
if (isa<StructType>(Ty))
return NoAlias;
break;
}
}
}
if (GEP1->getNumIndices() != GEP2->getNumIndices())
if (GEP1->getNumIndices() != GEP2->getNumIndices() ||
GEP1->getNumIndices() < 2)
return MayAlias;
// If we don't know the size of the accesses through both GEPs, we can't

36
llvm/test/Analysis/BasicAA/noalias-structure.ll
View File

@ -1,36 +0,0 @@
; RUN: opt < %s -basicaa -aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
%struct.Type = type { [10 x i32], i32 }
@Foo = external global %struct.Type, align 4
; /// Check that BasicAA claims no alias between different fileds of a structure
; void test() {
; for (unsigned i = 0 ; i < 10 ; i++)
; Foo.arr[i] += Foo.i;
; }
define void @test() {
; CHECK-LABEL: Function: test:
entry:
%0 = load i32, i32* getelementptr inbounds (%struct.Type, %struct.Type* @Foo, i64 0, i32 1), align 4
br label %for.body
for.cond.cleanup: ; preds = %for.body
ret void
for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
%arrayidx = getelementptr inbounds %struct.Type, %struct.Type* @Foo, i64 0, i32 0, i64 %indvars.iv
%1 = load i32, i32* %arrayidx, align 4
%add = add nsw i32 %1, %0
store i32 %add, i32* %arrayidx, align 4
; CHECK: NoAlias: i32* %arrayidx, i32* getelementptr inbounds (%struct.Type, %struct.Type* @Foo, i64 0, i32 1)
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond = icmp eq i64 %indvars.iv.next, 10
br i1 %exitcond, label %for.cond.cleanup, label %for.body
}

336
llvm/test/Transforms/LoopVectorize/global_alias.ll
View File

@ -765,18 +765,22 @@ for.end: ; preds = %for.cond
ret i32 %7
}
; /// Different objects, swapped induction
; int noAlias15(int a) {
;; === Now, the tests that we could vectorize with induction changes or run-time checks ===
; /// Different objects, swapped induction, alias at the end
; int mayAlias01 (int a) {
; int i;
; for (i=0; i<SIZE; i++)
; Foo.A[i] = Foo.B[SIZE-i-1] + a;
; return Foo.A[a];
; }
; CHECK-LABEL: define i32 @noAlias15(
; CHECK: add nsw <4 x i32>
; CHECK-LABEL: define i32 @mayAlias01(
; CHECK-NOT: add nsw <4 x i32>
; CHECK: ret
define i32 @noAlias15(i32 %a) nounwind {
define i32 @mayAlias01(i32 %a) nounwind {
entry:
%a.addr = alloca i32, align 4
%i = alloca i32, align 4
@ -815,18 +819,18 @@ for.end: ; preds = %for.cond
ret i32 %7
}
; /// Different objects, swapped induction
; int noAlias16 (int a) {
; /// Different objects, swapped induction, alias at the beginning
; int mayAlias02 (int a) {
; int i;
; for (i=0; i<SIZE; i++)
; Foo.A[SIZE-i-1] = Foo.B[i] + a;
; return Foo.A[a];
; }
; CHECK-LABEL: define i32 @noAlias16(
; CHECK: add nsw <4 x i32>
; CHECK-LABEL: define i32 @mayAlias02(
; CHECK-NOT: add nsw <4 x i32>
; CHECK: ret
define i32 @noAlias16(i32 %a) nounwind {
define i32 @mayAlias02(i32 %a) nounwind {
entry:
%a.addr = alloca i32, align 4
%i = alloca i32, align 4
@ -865,171 +869,18 @@ for.end: ; preds = %for.cond
ret i32 %7
}
;; === Ignore undefined behavior ===
; int noAlias17(int a) {
; int i;
; for (i=0; i<SIZE; i++)
; Foo.A[i+10] = Foo.B[SIZE-i-1] + a;
; return Foo.A[a];
; }
; CHECK-LABEL: define i32 @noAlias17(
; CHECK: add nsw <4 x i32>
; CHECK: ret
define i32 @noAlias17(i32 %a) nounwind {
entry:
%a.addr = alloca i32, align 4
%i = alloca i32, align 4
store i32 %a, i32* %a.addr, align 4
store i32 0, i32* %i, align 4
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%0 = load i32, i32* %i, align 4
%cmp = icmp slt i32 %0, 100
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%1 = load i32, i32* %i, align 4
%sub = sub nsw i32 100, %1
%sub1 = sub nsw i32 %sub, 1
%arrayidx = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 2), i32 0, i32 %sub1
%2 = load i32, i32* %arrayidx, align 4
%3 = load i32, i32* %a.addr, align 4
%add = add nsw i32 %2, %3
%4 = load i32, i32* %i, align 4
%add2 = add nsw i32 %4, 10
%arrayidx3 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %add2
store i32 %add, i32* %arrayidx3, align 4
br label %for.inc
for.inc: ; preds = %for.body
%5 = load i32, i32* %i, align 4
%inc = add nsw i32 %5, 1
store i32 %inc, i32* %i, align 4
br label %for.cond
for.end: ; preds = %for.cond
%6 = load i32, i32* %a.addr, align 4
%arrayidx4 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %6
%7 = load i32, i32* %arrayidx4, align 4
ret i32 %7
}
; int noAlias18(int a) {
; int i;
; for (i=0; i<SIZE; i++)
; Foo.A[i] = Foo.B[SIZE-i-10] + a;
; return Foo.A[a];
; }
; CHECK-LABEL: define i32 @noAlias18(
; CHECK: add nsw <4 x i32>
; CHECK: ret
define i32 @noAlias18(i32 %a) nounwind {
entry:
%a.addr = alloca i32, align 4
%i = alloca i32, align 4
store i32 %a, i32* %a.addr, align 4
store i32 0, i32* %i, align 4
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%0 = load i32, i32* %i, align 4
%cmp = icmp slt i32 %0, 100
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%1 = load i32, i32* %i, align 4
%sub = sub nsw i32 100, %1
%sub1 = sub nsw i32 %sub, 10
%arrayidx = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 2), i32 0, i32 %sub1
%2 = load i32, i32* %arrayidx, align 4
%3 = load i32, i32* %a.addr, align 4
%add = add nsw i32 %2, %3
%4 = load i32, i32* %i, align 4
%arrayidx2 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %4
store i32 %add, i32* %arrayidx2, align 4
br label %for.inc
for.inc: ; preds = %for.body
%5 = load i32, i32* %i, align 4
%inc = add nsw i32 %5, 1
store i32 %inc, i32* %i, align 4
br label %for.cond
for.end: ; preds = %for.cond
%6 = load i32, i32* %a.addr, align 4
%arrayidx3 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %6
%7 = load i32, i32* %arrayidx3, align 4
ret i32 %7
}
; int noAlias19(int a) {
; int i;
; for (i=0; i<SIZE; i++)
; Foo.A[i+10] = Foo.B[SIZE-i-10] + a;
; return Foo.A[a];
; }
; CHECK-LABEL: define i32 @noAlias19(
; CHECK: add nsw <4 x i32>
; CHECK: ret
define i32 @noAlias19(i32 %a) nounwind {
entry:
%a.addr = alloca i32, align 4
%i = alloca i32, align 4
store i32 %a, i32* %a.addr, align 4
store i32 0, i32* %i, align 4
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%0 = load i32, i32* %i, align 4
%cmp = icmp slt i32 %0, 100
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%1 = load i32, i32* %i, align 4
%sub = sub nsw i32 100, %1
%sub1 = sub nsw i32 %sub, 10
%arrayidx = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 2), i32 0, i32 %sub1
%2 = load i32, i32* %arrayidx, align 4
%3 = load i32, i32* %a.addr, align 4
%add = add nsw i32 %2, %3
%4 = load i32, i32* %i, align 4
%add2 = add nsw i32 %4, 10
%arrayidx3 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %add2
store i32 %add, i32* %arrayidx3, align 4
br label %for.inc
for.inc: ; preds = %for.body
%5 = load i32, i32* %i, align 4
%inc = add nsw i32 %5, 1
store i32 %inc, i32* %i, align 4
br label %for.cond
for.end: ; preds = %for.cond
%6 = load i32, i32* %a.addr, align 4
%arrayidx4 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %6
%7 = load i32, i32* %arrayidx4, align 4
ret i32 %7
}
; /// Pointer access, run-time check added
; int mayAlias01 (int a) {
; int mayAlias03 (int a) {
; int i;
; for (i=0; i<SIZE; i++)
; *(PA+i) = *(PB+SIZE-i-1) + a;
; return *(PA+a);
; }
; CHECK-LABEL: define i32 @mayAlias01(
; CHECK-LABEL: define i32 @mayAlias03(
; CHECK-NOT: add nsw <4 x i32>
; CHECK: ret
define i32 @mayAlias01(i32 %a) nounwind {
define i32 @mayAlias03(i32 %a) nounwind {
entry:
%a.addr = alloca i32, align 4
%i = alloca i32, align 4
@ -1071,3 +922,156 @@ for.end: ; preds = %for.cond
%10 = load i32, i32* %add.ptr4, align 4
ret i32 %10
}
;; === Finally, the tests that should only vectorize with care (or if we ignore undefined behaviour at all) ===
; int mustAlias01 (int a) {
; int i;
; for (i=0; i<SIZE; i++)
; Foo.A[i+10] = Foo.B[SIZE-i-1] + a;
; return Foo.A[a];
; }
; CHECK-LABEL: define i32 @mustAlias01(
; CHECK-NOT: add nsw <4 x i32>
; CHECK: ret
define i32 @mustAlias01(i32 %a) nounwind {
entry:
%a.addr = alloca i32, align 4
%i = alloca i32, align 4
store i32 %a, i32* %a.addr, align 4
store i32 0, i32* %i, align 4
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%0 = load i32, i32* %i, align 4
%cmp = icmp slt i32 %0, 100
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%1 = load i32, i32* %i, align 4
%sub = sub nsw i32 100, %1
%sub1 = sub nsw i32 %sub, 1
%arrayidx = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 2), i32 0, i32 %sub1
%2 = load i32, i32* %arrayidx, align 4
%3 = load i32, i32* %a.addr, align 4
%add = add nsw i32 %2, %3
%4 = load i32, i32* %i, align 4
%add2 = add nsw i32 %4, 10
%arrayidx3 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %add2
store i32 %add, i32* %arrayidx3, align 4
br label %for.inc
for.inc: ; preds = %for.body
%5 = load i32, i32* %i, align 4
%inc = add nsw i32 %5, 1
store i32 %inc, i32* %i, align 4
br label %for.cond
for.end: ; preds = %for.cond
%6 = load i32, i32* %a.addr, align 4
%arrayidx4 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %6
%7 = load i32, i32* %arrayidx4, align 4
ret i32 %7
}
; int mustAlias02 (int a) {
; int i;
; for (i=0; i<SIZE; i++)
; Foo.A[i] = Foo.B[SIZE-i-10] + a;
; return Foo.A[a];
; }
; CHECK-LABEL: define i32 @mustAlias02(
; CHECK-NOT: add nsw <4 x i32>
; CHECK: ret
define i32 @mustAlias02(i32 %a) nounwind {
entry:
%a.addr = alloca i32, align 4
%i = alloca i32, align 4
store i32 %a, i32* %a.addr, align 4
store i32 0, i32* %i, align 4
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%0 = load i32, i32* %i, align 4
%cmp = icmp slt i32 %0, 100
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%1 = load i32, i32* %i, align 4
%sub = sub nsw i32 100, %1
%sub1 = sub nsw i32 %sub, 10
%arrayidx = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 2), i32 0, i32 %sub1
%2 = load i32, i32* %arrayidx, align 4
%3 = load i32, i32* %a.addr, align 4
%add = add nsw i32 %2, %3
%4 = load i32, i32* %i, align 4
%arrayidx2 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %4
store i32 %add, i32* %arrayidx2, align 4
br label %for.inc
for.inc: ; preds = %for.body
%5 = load i32, i32* %i, align 4
%inc = add nsw i32 %5, 1
store i32 %inc, i32* %i, align 4
br label %for.cond
for.end: ; preds = %for.cond
%6 = load i32, i32* %a.addr, align 4
%arrayidx3 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %6
%7 = load i32, i32* %arrayidx3, align 4
ret i32 %7
}
; int mustAlias03 (int a) {
; int i;
; for (i=0; i<SIZE; i++)
; Foo.A[i+10] = Foo.B[SIZE-i-10] + a;
; return Foo.A[a];
; }
; CHECK-LABEL: define i32 @mustAlias03(
; CHECK-NOT: add nsw <4 x i32>
; CHECK: ret
define i32 @mustAlias03(i32 %a) nounwind {
entry:
%a.addr = alloca i32, align 4
%i = alloca i32, align 4
store i32 %a, i32* %a.addr, align 4
store i32 0, i32* %i, align 4
br label %for.cond
for.cond: ; preds = %for.inc, %entry
%0 = load i32, i32* %i, align 4
%cmp = icmp slt i32 %0, 100
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
%1 = load i32, i32* %i, align 4
%sub = sub nsw i32 100, %1
%sub1 = sub nsw i32 %sub, 10
%arrayidx = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 2), i32 0, i32 %sub1
%2 = load i32, i32* %arrayidx, align 4
%3 = load i32, i32* %a.addr, align 4
%add = add nsw i32 %2, %3
%4 = load i32, i32* %i, align 4
%add2 = add nsw i32 %4, 10
%arrayidx3 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %add2
store i32 %add, i32* %arrayidx3, align 4
br label %for.inc
for.inc: ; preds = %for.body
%5 = load i32, i32* %i, align 4
%inc = add nsw i32 %5, 1
store i32 %inc, i32* %i, align 4
br label %for.cond
for.end: ; preds = %for.cond
%6 = load i32, i32* %a.addr, align 4
%arrayidx4 = getelementptr inbounds [100 x i32], [100 x i32]* getelementptr inbounds (%struct.anon, %struct.anon* @Foo, i32 0, i32 0), i32 0, i32 %6
%7 = load i32, i32* %arrayidx4, align 4
ret i32 %7
}