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LoopVectorize: Invert case when we use a vector cmp value to query select cost 

We generate a select with a vectorized condition argument when the condition is
NOT loop invariant. Not the other way around.

llvm-svn: 177098
This commit is contained in:
Arnold Schwaighofer 2013-03-14 18:54:36 +00:00
parent 7cc48f45cb
commit c63cf3a0ae
2 changed files with 63 additions and 1 deletions
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2
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -3338,7 +3338,7 @@ LoopVectorizationCostModel::getInstructionCost(Instruction *I, unsigned VF) {
const SCEV *CondSCEV = SE->getSCEV(SI->getCondition()); const SCEV *CondSCEV = SE->getSCEV(SI->getCondition());
bool ScalarCond = (SE->isLoopInvariant(CondSCEV, TheLoop)); bool ScalarCond = (SE->isLoopInvariant(CondSCEV, TheLoop));
Type *CondTy = SI->getCondition()->getType(); Type *CondTy = SI->getCondition()->getType();
if (ScalarCond) if (!ScalarCond)
CondTy = VectorType::get(CondTy, VF); CondTy = VectorType::get(CondTy, VF);
return TTI.getCmpSelInstrCost(I->getOpcode(), VectorTy, CondTy); return TTI.getCmpSelInstrCost(I->getOpcode(), VectorTy, CondTy);

62
llvm/test/Transforms/LoopVectorize/X86/vector-scalar-select-cost.ll Normal file
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@ -0,0 +1,62 @@
; RUN: opt < %s -loop-vectorize -mcpu=core2 -debug-only=loop-vectorize 2>&1 -S | FileCheck %s
; Make sure we use the right select kind when querying select costs.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.8.0"
@a = common global [2048 x i32] zeroinitializer, align 16
@b = common global [2048 x i32] zeroinitializer, align 16
@c = common global [2048 x i32] zeroinitializer, align 16
; CHECK: Checking a loop in "scalarselect"
define void @scalarselect(i1 %cond) nounwind uwtable ssp {
br label %1
; <label>:1 ; preds = %1, %0
%indvars.iv = phi i64 [ 0, %0 ], [ %indvars.iv.next, %1 ]
%2 = getelementptr inbounds [2048 x i32]* @b, i64 0, i64 %indvars.iv
%3 = load i32* %2, align 4
%4 = getelementptr inbounds [2048 x i32]* @c, i64 0, i64 %indvars.iv
%5 = load i32* %4, align 4
%6 = add nsw i32 %5, %3
%7 = getelementptr inbounds [2048 x i32]* @a, i64 0, i64 %indvars.iv
; A scalar select has a cost of 1 on core2
; CHECK: cost of 1 for VF 2 {{.*}} select i1 %cond, i32 %6, i32 0
%sel = select i1 %cond, i32 %6, i32 zeroinitializer
store i32 %sel, i32* %7, align 4
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, 256
br i1 %exitcond, label %8, label %1
; <label>:8 ; preds = %1
ret void
}
; CHECK: Checking a loop in "vectorselect"
define void @vectorselect(i1 %cond) nounwind uwtable ssp {
br label %1
; <label>:1 ; preds = %1, %0
%indvars.iv = phi i64 [ 0, %0 ], [ %indvars.iv.next, %1 ]
%2 = getelementptr inbounds [2048 x i32]* @b, i64 0, i64 %indvars.iv
%3 = load i32* %2, align 4
%4 = getelementptr inbounds [2048 x i32]* @c, i64 0, i64 %indvars.iv
%5 = load i32* %4, align 4
%6 = add nsw i32 %5, %3
%7 = getelementptr inbounds [2048 x i32]* @a, i64 0, i64 %indvars.iv
%8 = icmp ult i64 %indvars.iv, 8
; A vector select has a cost of 4 on core2
; CHECK: cost of 4 for VF 2 {{.*}} select i1 %8, i32 %6, i32 0
%sel = select i1 %8, i32 %6, i32 zeroinitializer
store i32 %sel, i32* %7, align 4
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, 256
br i1 %exitcond, label %9, label %1
; <label>:9 ; preds = %1
ret void
}