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-rw-r--r--lib/Analysis/BasicAliasAnalysis.cpp18
-rw-r--r--lib/Target/README.txt17
-rw-r--r--test/Analysis/BasicAA/gep-alias.ll14
3 files changed, 27 insertions, 22 deletions
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index fb6b9df..f8d8873 100644
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -14,8 +14,6 @@
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/CaptureTracking.h"
-#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
@@ -26,6 +24,9 @@
#include "llvm/IntrinsicInst.h"
#include "llvm/Operator.h"
#include "llvm/Pass.h"
+#include "llvm/Analysis/CaptureTracking.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Target/TargetData.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
@@ -381,15 +382,22 @@ BasicAliasAnalysis::getModRefInfo(CallSite CS1, CallSite CS2) {
/// GetLinearExpression - Analyze the specified value as a linear expression:
/// "A*V + B". Return the scale and offset values as APInts and return V as a
/// Value*. The incoming Value is known to be a scalar integer.
-static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset) {
+static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset,
+ const TargetData *TD) {
assert(isa<IntegerType>(V->getType()) && "Not an integer value");
if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(V)) {
if (ConstantInt *RHSC = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
switch (BOp->getOpcode()) {
default: break;
+ case Instruction::Or:
+ // X|C == X+C if all the bits in C are unset in X. Otherwise we can't
+ // analyze it.
+ if (!MaskedValueIsZero(BOp->getOperand(0), RHSC->getValue(), TD))
+ break;
+ // FALL THROUGH.
case Instruction::Add:
- V = GetLinearExpression(BOp->getOperand(0), Scale, Offset);
+ V = GetLinearExpression(BOp->getOperand(0), Scale, Offset, TD);
Offset += RHSC->getValue();
return V;
// TODO: SHL, MUL, OR.
@@ -482,7 +490,7 @@ static const Value *DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
unsigned Width = cast<IntegerType>(Index->getType())->getBitWidth();
APInt IndexScale(Width, 0), IndexOffset(Width, 0);
- Index = GetLinearExpression(Index, IndexScale, IndexOffset);
+ Index = GetLinearExpression(Index, IndexScale, IndexOffset, TD);
Scale *= IndexScale.getZExtValue();
BaseOffs += IndexOffset.getZExtValue()*Scale;
diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index 3096f95..2db5808 100644
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -443,23 +443,6 @@ entry:
//===---------------------------------------------------------------------===//
-"basicaa" should know how to look through "or" instructions that act like add
-instructions. For example in this code, the x*4+1 is turned into x*4 | 1, and
-basicaa can't analyze the array subscript, leading to duplicated loads in the
-generated code:
-
-void test(int X, int Y, int a[]) {
-int i;
- for (i=2; i<1000; i+=4) {
- a[i+0] = a[i-1+0]*a[i-2+0];
- a[i+1] = a[i-1+1]*a[i-2+1];
- a[i+2] = a[i-1+2]*a[i-2+2];
- a[i+3] = a[i-1+3]*a[i-2+3];
- }
-}
-
-//===---------------------------------------------------------------------===//
-
We should investigate an instruction sinking pass. Consider this silly
example in pic mode:
diff --git a/test/Analysis/BasicAA/gep-alias.ll b/test/Analysis/BasicAA/gep-alias.ll
index 0c5f7ac..320c990 100644
--- a/test/Analysis/BasicAA/gep-alias.ll
+++ b/test/Analysis/BasicAA/gep-alias.ll
@@ -86,4 +86,18 @@ define i32 @test5(i32* %p, i64 %i) {
; CHECK: ret i32 0
}
+; P[i] != p[(i*4)|1]
+define i32 @test6(i32* %p, i64 %i1) {
+ %i = shl i64 %i1, 2
+ %pi = getelementptr i32* %p, i64 %i
+ %i.next = or i64 %i, 1
+ %pi.next = getelementptr i32* %p, i64 %i.next
+ %x = load i32* %pi
+ store i32 42, i32* %pi.next
+ %y = load i32* %pi
+ %z = sub i32 %x, %y
+ ret i32 %z
+; CHECK: @test6
+; CHECK: ret i32 0
+}