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Teach FoldBitCast to be able to handle bitcasts from (e.g.) i128 -> <4 x float>.

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This allows us to simplify this:
union vec2d {
    double e[2];
    double v __attribute__((vector_size(16)));
};
typedef union vec2d vec2d;

static vec2d a={{1,2}}, b={{3,4}};
    
vec2d foo () {
    return (vec2d){ .v = a.v + b.v * (vec2d){{5,5}}.v };
}

down to:

define %0 @foo() nounwind ssp {
entry:
  %mrv5 = insertvalue %0 undef, double 1.600000e+01, 0 ; <%0> [#uses=1]
  %mrv6 = insertvalue %0 %mrv5, double 2.200000e+01, 1 ; <%0> [#uses=1]
  ret %0 %mrv6
}

instead of:

define %0 @foo() nounwind ssp {
entry:
  %mrv5 = insertvalue %0 undef, double extractelement (<2 x double> fadd (<2 x double> fmul (<2 x double> bitcast (<1 x i128> <i128 85174437667405312423031577302488055808> to <2 x double>), <2 x double> <double 3.000000e+00, double 4.000000e+00>), <2 x double> <double 1.000000e+00, double 2.000000e+00>), i32 0), 0 ; <%0> [#uses=1]
  %mrv6 = insertvalue %0 %mrv5, double extractelement (<2 x double> fadd (<2 x double> fmul (<2 x double> bitcast (<1 x i128> <i128 85174437667405312423031577302488055808> to <2 x double>), <2 x double> <double 3.000000e+00, double 4.000000e+00>), <2 x double> <double 1.000000e+00, double 2.000000e+00>), i32 1), 1 ; <%0> [#uses=1]
  ret %0 %mrv6
}



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85040 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-10-25 06:15:37 +00:00
parent 6333c3959b
commit 93798daa3e
1 changed files with 13 additions and 4 deletions
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17
lib/Analysis/ConstantFolding.cpp
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@ -44,15 +44,24 @@ using namespace llvm;
/// ConstantExpr if unfoldable.
static Constant *FoldBitCast(Constant *C, const Type *DestTy,
const TargetData &TD) {
// This only handles casts to vectors currently.
const VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
if (DestVTy == 0)
return ConstantExpr::getBitCast(C, DestTy);
// If this is a scalar -> vector cast, convert the input into a <1 x scalar>
// vector so the code below can handle it uniformly.
if (isa<ConstantFP>(C) || isa<ConstantInt>(C)) {
Constant *Ops = C; // don't take the address of C!
return FoldBitCast(ConstantVector::get(&Ops, 1), DestTy, TD);
}
// If this is a bitcast from constant vector -> vector, fold it.
ConstantVector *CV = dyn_cast<ConstantVector>(C);
if (CV == 0)
return ConstantExpr::getBitCast(C, DestTy);
const VectorType *DestVTy = dyn_cast<VectorType>(DestTy);
if (DestVTy == 0)
return ConstantExpr::getBitCast(C, DestTy);
// If the element types match, VMCore can fold it.
unsigned NumDstElt = DestVTy->getNumElements();
unsigned NumSrcElt = CV->getNumOperands();