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Make bitcast, extractelement, and insertelement considered cheap for speculation.

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This helps more branches into selects. On R600,
vectors are cheap and anything that helps
remove branches is very good.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209914 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Matt Arsenault 2014-05-30 18:34:43 +00:00
parent 731d23ed42
commit c4e0611d86
2 changed files with 63 additions and 0 deletions
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3
lib/Transforms/Utils/SimplifyCFG.cpp
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@ -227,6 +227,9 @@ static unsigned ComputeSpeculationCost(const User *I) {
case Instruction::Trunc:
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::BitCast:
case Instruction::ExtractElement:
case Instruction::InsertElement:
return 1; // These are all cheap.
case Instruction::Call:

60
test/Transforms/SimplifyCFG/speculate-vector-ops.ll Normal file
View File

@ -0,0 +1,60 @@
; RUN: opt -S -simplifycfg < %s | FileCheck %s
define i32 @speculate_vector_extract(i32 %d, <4 x i32> %v) #0 {
; CHECK-LABEL: @speculate_vector_extract(
; CHECK-NOT: br
entry:
%conv = insertelement <4 x i32> undef, i32 %d, i32 0
%conv2 = insertelement <4 x i32> %conv, i32 %d, i32 1
%conv3 = insertelement <4 x i32> %conv2, i32 %d, i32 2
%conv4 = insertelement <4 x i32> %conv3, i32 %d, i32 3
%tmp6 = add nsw <4 x i32> %conv4, <i32 0, i32 -1, i32 -2, i32 -3>
%cmp = icmp eq <4 x i32> %tmp6, zeroinitializer
%cmp.ext = sext <4 x i1> %cmp to <4 x i32>
%tmp8 = extractelement <4 x i32> %cmp.ext, i32 0
%tobool = icmp eq i32 %tmp8, 0
br i1 %tobool, label %cond.else, label %cond.then
return: ; preds = %cond.end28
ret i32 %cond32
cond.then: ; preds = %entry
%tmp10 = extractelement <4 x i32> %v, i32 0
br label %cond.end
cond.else: ; preds = %entry
%tmp12 = extractelement <4 x i32> %v, i32 3
br label %cond.end
cond.end: ; preds = %cond.else, %cond.then
%cond = phi i32 [ %tmp10, %cond.then ], [ %tmp12, %cond.else ]
%tmp14 = extractelement <4 x i32> %cmp.ext, i32 1
%tobool15 = icmp eq i32 %tmp14, 0
br i1 %tobool15, label %cond.else17, label %cond.then16
cond.then16: ; preds = %cond.end
%tmp20 = extractelement <4 x i32> %v, i32 1
br label %cond.end18
cond.else17: ; preds = %cond.end
br label %cond.end18
cond.end18: ; preds = %cond.else17, %cond.then16
%cond22 = phi i32 [ %tmp20, %cond.then16 ], [ %cond, %cond.else17 ]
%tmp24 = extractelement <4 x i32> %cmp.ext, i32 2
%tobool25 = icmp eq i32 %tmp24, 0
br i1 %tobool25, label %cond.else27, label %cond.then26
cond.then26: ; preds = %cond.end18
%tmp30 = extractelement <4 x i32> %v, i32 2
br label %cond.end28
cond.else27: ; preds = %cond.end18
br label %cond.end28
cond.end28: ; preds = %cond.else27, %cond.then26
%cond32 = phi i32 [ %tmp30, %cond.then26 ], [ %cond22, %cond.else27 ]
br label %return
}
attributes #0 = { nounwind }