[llvm-commits] [llvm] r97793 - in /llvm/trunk: include/llvm/Analysis/ValueTracking.h lib/Analysis/ValueTracking.cpp lib/Transforms/Scalar/SimplifyLibCalls.cpp
Eric Christopher
echristo at apple.com
Thu Mar 4 22:58:57 PST 2010
Author: echristo
Date: Fri Mar 5 00:58:57 2010
New Revision: 97793
URL: http://llvm.org/viewvc/llvm-project?rev=97793&view=rev
Log:
Move GetStringLength and helper from SimplifyLibCalls to ValueTracking.
No functionality change.
Modified:
llvm/trunk/include/llvm/Analysis/ValueTracking.h
llvm/trunk/lib/Analysis/ValueTracking.cpp
llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp
Modified: llvm/trunk/include/llvm/Analysis/ValueTracking.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ValueTracking.h?rev=97793&r1=97792&r2=97793&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ValueTracking.h (original)
+++ llvm/trunk/include/llvm/Analysis/ValueTracking.h Fri Mar 5 00:58:57 2010
@@ -124,6 +124,10 @@
/// character is included in the result string.
bool GetConstantStringInfo(Value *V, std::string &Str, uint64_t Offset = 0,
bool StopAtNul = true);
+
+ /// GetStringLength - If we can compute the length of the string pointed to by
+ /// the specified pointer, return 'len+1'. If we can't, return 0.
+ uint64_t GetStringLength(Value *V);
} // end namespace llvm
#endif
Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=97793&r1=97792&r2=97793&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Fri Mar 5 00:58:57 2010
@@ -23,6 +23,7 @@
#include "llvm/Target/TargetData.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include <cstring>
using namespace llvm;
@@ -1436,3 +1437,131 @@
// The array isn't null terminated, but maybe this is a memcpy, not a strcpy.
return true;
}
+
+// These next two are very similar to the above, but also look through PHI
+// nodes.
+// TODO: See if we can integrate these two together.
+
+/// GetStringLengthH - If we can compute the length of the string pointed to by
+/// the specified pointer, return 'len+1'. If we can't, return 0.
+static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
+ // Look through noop bitcast instructions.
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
+ return GetStringLengthH(BCI->getOperand(0), PHIs);
+
+ // If this is a PHI node, there are two cases: either we have already seen it
+ // or we haven't.
+ if (PHINode *PN = dyn_cast<PHINode>(V)) {
+ if (!PHIs.insert(PN))
+ return ~0ULL; // already in the set.
+
+ // If it was new, see if all the input strings are the same length.
+ uint64_t LenSoFar = ~0ULL;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs);
+ if (Len == 0) return 0; // Unknown length -> unknown.
+
+ if (Len == ~0ULL) continue;
+
+ if (Len != LenSoFar && LenSoFar != ~0ULL)
+ return 0; // Disagree -> unknown.
+ LenSoFar = Len;
+ }
+
+ // Success, all agree.
+ return LenSoFar;
+ }
+
+ // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y)
+ if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
+ uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs);
+ if (Len1 == 0) return 0;
+ uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs);
+ if (Len2 == 0) return 0;
+ if (Len1 == ~0ULL) return Len2;
+ if (Len2 == ~0ULL) return Len1;
+ if (Len1 != Len2) return 0;
+ return Len1;
+ }
+
+ // If the value is not a GEP instruction nor a constant expression with a
+ // GEP instruction, then return unknown.
+ User *GEP = 0;
+ if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
+ GEP = GEPI;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
+ if (CE->getOpcode() != Instruction::GetElementPtr)
+ return 0;
+ GEP = CE;
+ } else {
+ return 0;
+ }
+
+ // Make sure the GEP has exactly three arguments.
+ if (GEP->getNumOperands() != 3)
+ return 0;
+
+ // Check to make sure that the first operand of the GEP is an integer and
+ // has value 0 so that we are sure we're indexing into the initializer.
+ if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
+ if (!Idx->isZero())
+ return 0;
+ } else
+ return 0;
+
+ // If the second index isn't a ConstantInt, then this is a variable index
+ // into the array. If this occurs, we can't say anything meaningful about
+ // the string.
+ uint64_t StartIdx = 0;
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
+ StartIdx = CI->getZExtValue();
+ else
+ return 0;
+
+ // The GEP instruction, constant or instruction, must reference a global
+ // variable that is a constant and is initialized. The referenced constant
+ // initializer is the array that we'll use for optimization.
+ GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
+ if (!GV || !GV->isConstant() || !GV->hasInitializer() ||
+ GV->mayBeOverridden())
+ return 0;
+ Constant *GlobalInit = GV->getInitializer();
+
+ // Handle the ConstantAggregateZero case, which is a degenerate case. The
+ // initializer is constant zero so the length of the string must be zero.
+ if (isa<ConstantAggregateZero>(GlobalInit))
+ return 1; // Len = 0 offset by 1.
+
+ // Must be a Constant Array
+ ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
+ if (!Array || !Array->getType()->getElementType()->isIntegerTy(8))
+ return false;
+
+ // Get the number of elements in the array
+ uint64_t NumElts = Array->getType()->getNumElements();
+
+ // Traverse the constant array from StartIdx (derived above) which is
+ // the place the GEP refers to in the array.
+ for (unsigned i = StartIdx; i != NumElts; ++i) {
+ Constant *Elt = Array->getOperand(i);
+ ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
+ if (!CI) // This array isn't suitable, non-int initializer.
+ return 0;
+ if (CI->isZero())
+ return i-StartIdx+1; // We found end of string, success!
+ }
+
+ return 0; // The array isn't null terminated, conservatively return 'unknown'.
+}
+
+/// GetStringLength - If we can compute the length of the string pointed to by
+/// the specified pointer, return 'len+1'. If we can't, return 0.
+uint64_t llvm::GetStringLength(Value *V) {
+ if (!V->getType()->isPointerTy()) return 0;
+
+ SmallPtrSet<PHINode*, 32> PHIs;
+ uint64_t Len = GetStringLengthH(V, PHIs);
+ // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return
+ // an empty string as a length.
+ return Len == ~0ULL ? 1 : Len;
+}
Modified: llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp?rev=97793&r1=97792&r2=97793&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SimplifyLibCalls.cpp Fri Mar 5 00:58:57 2010
@@ -433,130 +433,6 @@
// Helper Functions
//===----------------------------------------------------------------------===//
-/// GetStringLengthH - If we can compute the length of the string pointed to by
-/// the specified pointer, return 'len+1'. If we can't, return 0.
-static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
- // Look through noop bitcast instructions.
- if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
- return GetStringLengthH(BCI->getOperand(0), PHIs);
-
- // If this is a PHI node, there are two cases: either we have already seen it
- // or we haven't.
- if (PHINode *PN = dyn_cast<PHINode>(V)) {
- if (!PHIs.insert(PN))
- return ~0ULL; // already in the set.
-
- // If it was new, see if all the input strings are the same length.
- uint64_t LenSoFar = ~0ULL;
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
- uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs);
- if (Len == 0) return 0; // Unknown length -> unknown.
-
- if (Len == ~0ULL) continue;
-
- if (Len != LenSoFar && LenSoFar != ~0ULL)
- return 0; // Disagree -> unknown.
- LenSoFar = Len;
- }
-
- // Success, all agree.
- return LenSoFar;
- }
-
- // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y)
- if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
- uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs);
- if (Len1 == 0) return 0;
- uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs);
- if (Len2 == 0) return 0;
- if (Len1 == ~0ULL) return Len2;
- if (Len2 == ~0ULL) return Len1;
- if (Len1 != Len2) return 0;
- return Len1;
- }
-
- // If the value is not a GEP instruction nor a constant expression with a
- // GEP instruction, then return unknown.
- User *GEP = 0;
- if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
- GEP = GEPI;
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
- if (CE->getOpcode() != Instruction::GetElementPtr)
- return 0;
- GEP = CE;
- } else {
- return 0;
- }
-
- // Make sure the GEP has exactly three arguments.
- if (GEP->getNumOperands() != 3)
- return 0;
-
- // Check to make sure that the first operand of the GEP is an integer and
- // has value 0 so that we are sure we're indexing into the initializer.
- if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
- if (!Idx->isZero())
- return 0;
- } else
- return 0;
-
- // If the second index isn't a ConstantInt, then this is a variable index
- // into the array. If this occurs, we can't say anything meaningful about
- // the string.
- uint64_t StartIdx = 0;
- if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
- StartIdx = CI->getZExtValue();
- else
- return 0;
-
- // The GEP instruction, constant or instruction, must reference a global
- // variable that is a constant and is initialized. The referenced constant
- // initializer is the array that we'll use for optimization.
- GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
- if (!GV || !GV->isConstant() || !GV->hasInitializer() ||
- GV->mayBeOverridden())
- return 0;
- Constant *GlobalInit = GV->getInitializer();
-
- // Handle the ConstantAggregateZero case, which is a degenerate case. The
- // initializer is constant zero so the length of the string must be zero.
- if (isa<ConstantAggregateZero>(GlobalInit))
- return 1; // Len = 0 offset by 1.
-
- // Must be a Constant Array
- ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
- if (!Array || !Array->getType()->getElementType()->isIntegerTy(8))
- return false;
-
- // Get the number of elements in the array
- uint64_t NumElts = Array->getType()->getNumElements();
-
- // Traverse the constant array from StartIdx (derived above) which is
- // the place the GEP refers to in the array.
- for (unsigned i = StartIdx; i != NumElts; ++i) {
- Constant *Elt = Array->getOperand(i);
- ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
- if (!CI) // This array isn't suitable, non-int initializer.
- return 0;
- if (CI->isZero())
- return i-StartIdx+1; // We found end of string, success!
- }
-
- return 0; // The array isn't null terminated, conservatively return 'unknown'.
-}
-
-/// GetStringLength - If we can compute the length of the string pointed to by
-/// the specified pointer, return 'len+1'. If we can't, return 0.
-static uint64_t GetStringLength(Value *V) {
- if (!V->getType()->isPointerTy()) return 0;
-
- SmallPtrSet<PHINode*, 32> PHIs;
- uint64_t Len = GetStringLengthH(V, PHIs);
- // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return
- // an empty string as a length.
- return Len == ~0ULL ? 1 : Len;
-}
-
/// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the
/// value is equal or not-equal to zero.
static bool IsOnlyUsedInZeroEqualityComparison(Value *V) {
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