[llvm] r174179 - InstSimplify: stripAndComputeConstantOffsets can be called with vectors of pointers too.

[Benjamin Kramer]

Author: d0k
Date: Fri Feb  1 09:21:10 2013
New Revision: 174179

URL: http://llvm.org/viewvc/llvm-project?rev=174179&view=rev
Log:
InstSimplify: stripAndComputeConstantOffsets can be called with vectors of pointers too.

Prepare it for vectors of pointers and handle simple cases. We don't handle
complicated cases because accumulateConstantOffset bails on pointer vectors.
Fixes selfhost on i386.

Modified:
    llvm/trunk/lib/Analysis/InstructionSimplify.cpp
    llvm/trunk/test/Transforms/InstSimplify/ptr_diff.ll

Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=174179&r1=174178&r2=174179&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Fri Feb  1 09:21:10 2013
@@ -667,9 +667,9 @@ Value *llvm::SimplifyAddInst(Value *Op0,
 /// This is very similar to GetPointerBaseWithConstantOffset except it doesn't
 /// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc.
 /// folding.
-static ConstantInt *stripAndComputeConstantOffsets(const DataLayout *TD,
-                                                   Value *&V) {
-  assert(V->getType()->isPointerTy());
+static Constant *stripAndComputeConstantOffsets(const DataLayout *TD,
+                                                Value *&V) {
+  assert(V->getType()->getScalarType()->isPointerTy());
 
   // Without DataLayout, just be conservative for now. Theoretically, more could
   // be done in this case.
@@ -697,11 +697,16 @@ static ConstantInt *stripAndComputeConst
     } else {
       break;
     }
-    assert(V->getType()->isPointerTy() && "Unexpected operand type!");
+    assert(V->getType()->getScalarType()->isPointerTy() &&
+           "Unexpected operand type!");
   } while (Visited.insert(V));
 
   Type *IntPtrTy = TD->getIntPtrType(V->getContext());
-  return cast<ConstantInt>(ConstantInt::get(IntPtrTy, Offset));
+  Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
+  if (V->getType()->isVectorTy())
+    return ConstantVector::getSplat(V->getType()->getVectorNumElements(),
+                                    OffsetIntPtr);
+  return OffsetIntPtr;
 }
 
 /// \brief Compute the constant difference between two pointer values.
@@ -1758,8 +1763,8 @@ static Constant *computePointerICmp(cons
   // numerous hazards. AliasAnalysis and its utilities rely on special rules
   // governing loads and stores which don't apply to icmps. Also, AliasAnalysis
   // doesn't need to guarantee pointer inequality when it says NoAlias.
-  ConstantInt *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
-  ConstantInt *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
+  Constant *LHSOffset = stripAndComputeConstantOffsets(TD, LHS);
+  Constant *RHSOffset = stripAndComputeConstantOffsets(TD, RHS);
 
   // If LHS and RHS are related via constant offsets to the same base
   // value, we can replace it with an icmp which just compares the offsets.
@@ -1799,11 +1804,14 @@ static Constant *computePointerICmp(cons
     // address, due to canonicalization and constant folding.
     if (isa<AllocaInst>(LHS) &&
         (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) {
+      ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset);
+      ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset);
       uint64_t LHSSize, RHSSize;
-      if (getObjectSize(LHS, LHSSize, TD, TLI) &&
+      if (LHSOffsetCI && RHSOffsetCI &&
+          getObjectSize(LHS, LHSSize, TD, TLI) &&
           getObjectSize(RHS, RHSSize, TD, TLI)) {
-        const APInt &LHSOffsetValue = LHSOffset->getValue();
-        const APInt &RHSOffsetValue = RHSOffset->getValue();
+        const APInt &LHSOffsetValue = LHSOffsetCI->getValue();
+        const APInt &RHSOffsetValue = RHSOffsetCI->getValue();
         if (!LHSOffsetValue.isNegative() &&
             !RHSOffsetValue.isNegative() &&
             LHSOffsetValue.ult(LHSSize) &&

Modified: llvm/trunk/test/Transforms/InstSimplify/ptr_diff.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/ptr_diff.ll?rev=174179&r1=174178&r2=174179&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/ptr_diff.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/ptr_diff.ll Fri Feb  1 09:21:10 2013
@@ -46,3 +46,14 @@ define i64 @ptrdiff3(i8* %ptr) {
   %diff = sub i64 %last.int, %first.int
   ret i64 %diff
 }
+
+define <4 x i32> @ptrdiff4(<4 x i8*> %arg) nounwind {
+; Handle simple cases of vectors of pointers.
+; CHECK: @ptrdiff4
+; CHECK: ret <4 x i32> zeroinitializer
+  %p1 = ptrtoint <4 x i8*> %arg to <4 x i32>
+  %bc = bitcast <4 x i8*> %arg to <4 x i32*>
+  %p2 = ptrtoint <4 x i32*> %bc to <4 x i32>
+  %sub = sub <4 x i32> %p1, %p2
+  ret <4 x i32> %sub
+}