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Simplify trunc(extend(x)) in SCEVs, just for completeness. Also fix some odd

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whitespace in the same file.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69870 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2009-04-23 05:15:08 +00:00
parent 03dac74d40
commit 5cd28fad15
2 changed files with 49 additions and 4 deletions
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16
lib/Analysis/ScalarEvolution.cpp
View File

@ -658,6 +658,14 @@ SCEVHandle ScalarEvolution::getTruncateExpr(const SCEVHandle &Op, const Type *Ty
if (SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
return getTruncateExpr(ST->getOperand(), Ty);
// trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
if (SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
return getTruncateOrSignExtend(SS->getOperand(), Ty);
// trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
if (SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
return getTruncateOrZeroExtend(SZ->getOperand(), Ty);
// If the input value is a chrec scev made out of constants, truncate
// all of the constants.
if (SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
@ -1152,7 +1160,7 @@ SCEVHandle ScalarEvolution::getAddRecExpr(const SCEVHandle &Start,
/// SCEVAddRecExpr::get - Get a add recurrence expression for the
/// specified loop. Simplify the expression as much as possible.
SCEVHandle ScalarEvolution::getAddRecExpr(std::vector<SCEVHandle> &Operands,
const Loop *L) {
const Loop *L) {
if (Operands.size() == 1) return Operands[0];
if (Operands.back()->isZero()) {
@ -1484,7 +1492,7 @@ SCEVHandle ScalarEvolution::getNotSCEV(const SCEVHandle &V) {
/// getMinusSCEV - Return a SCEV corresponding to LHS - RHS.
///
SCEVHandle ScalarEvolution::getMinusSCEV(const SCEVHandle &LHS,
const SCEVHandle &RHS) {
const SCEVHandle &RHS) {
// X - Y --> X + -Y
return getAddExpr(LHS, getNegativeSCEV(RHS));
}
@ -1494,7 +1502,7 @@ SCEVHandle ScalarEvolution::getMinusSCEV(const SCEVHandle &LHS,
/// extended.
SCEVHandle
ScalarEvolution::getTruncateOrZeroExtend(const SCEVHandle &V,
const Type *Ty) {
const Type *Ty) {
const Type *SrcTy = V->getType();
assert((SrcTy->isInteger() || (TD && isa<PointerType>(SrcTy))) &&
(Ty->isInteger() || (TD && isa<PointerType>(Ty))) &&
@ -1511,7 +1519,7 @@ ScalarEvolution::getTruncateOrZeroExtend(const SCEVHandle &V,
/// extended.
SCEVHandle
ScalarEvolution::getTruncateOrSignExtend(const SCEVHandle &V,
const Type *Ty) {
const Type *Ty) {
const Type *SrcTy = V->getType();
assert((SrcTy->isInteger() || (TD && isa<PointerType>(SrcTy))) &&
(Ty->isInteger() || (TD && isa<PointerType>(Ty))) &&

37
test/Analysis/ScalarEvolution/2009-04-22-TruncCast.ll Normal file
View File

@ -0,0 +1,37 @@
; RUN: llvm-as < %s | opt -analyze -scalar-evolution | grep truncate | not grep extend
define i16 @test1(i8 %x) {
%A = sext i8 %x to i32
%B = trunc i32 %A to i16
ret i16 %B
}
define i8 @test2(i16 %x) {
%A = sext i16 %x to i32
%B = trunc i32 %A to i8
ret i8 %B
}
define i16 @test3(i16 %x) {
%A = sext i16 %x to i32
%B = trunc i32 %A to i16
ret i16 %B
}
define i16 @test4(i8 %x) {
%A = zext i8 %x to i32
%B = trunc i32 %A to i16
ret i16 %B
}
define i8 @test5(i16 %x) {
%A = zext i16 %x to i32
%B = trunc i32 %A to i8
ret i8 %B
}
define i16 @test6(i16 %x) {
%A = zext i16 %x to i32
%B = trunc i32 %A to i16
ret i16 %B
}