Disable the optimization about promoting vector-element-access with symbolic index.

This optimization is unstable at this moment; it 
  1) block us on a very important application
  2) PR15200
  3) test6 and test7 in test/Transforms/ScalarRepl/dynamic-vector-gep.ll
     (the CHECK command compare the output against wrong result)

   I personally believe this optimization should not have any impact on the
autovectorized code, as auto-vectorizer is supposed to put gather/scatter
in a "right" way.  Although in theory downstream optimizaters might reveal 
some gather/scatter optimization opportunities, the chance is quite slim.

   For the hand-crafted vectorizing code, in term of redundancy elimination,
load-CSE, copy-propagation and DSE can collectively achieve the same result,
but in much simpler way. On the other hand, these optimizers are able to 
improve the code in a incremental way; in contrast, SROA is sort of all-or-none
approach. However, SROA might slighly win in stack size, as it tries to figure 
out a stretch of memory tightenly cover the area accessed by the dynamic index.

 rdar://13174884
 PR15200



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@178912 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Shuxin Yang 2013-04-05 21:07:08 +00:00
parent 84058c9acc
commit 2da70d1792
2 changed files with 2 additions and 178 deletions

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@ -1724,17 +1724,8 @@ void SROA::isSafeGEP(GetElementPtrInst *GEPI,
continue;
ConstantInt *IdxVal = dyn_cast<ConstantInt>(GEPIt.getOperand());
if (!IdxVal) {
// Non constant GEPs are only a problem on arrays, structs, and pointers
// Vectors can be dynamically indexed.
// FIXME: Add support for dynamic indexing on arrays. This should be
// ok on any subarrays of the alloca array, eg, a[0][i] is ok, but a[i][0]
// isn't.
if (!(*GEPIt)->isVectorTy())
return MarkUnsafe(Info, GEPI);
NonConstant = true;
NonConstantIdxSize = TD->getTypeAllocSize(*GEPIt);
}
if (!IdxVal)
return MarkUnsafe(Info, GEPI);
}
// Compute the offset due to this GEP and check if the alloca has a

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@ -1,167 +0,0 @@
; RUN: opt < %s -scalarrepl -S | FileCheck %s
target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64"
target triple = "x86_64-apple-darwin10.0.0"
; CHECK: @test1
; CHECK: %[[alloc:[\.a-z0-9]*]] = alloca <4 x float>
; CHECK: store <4 x float> zeroinitializer, <4 x float>* %[[alloc]]
; CHECK: memset
; CHECK: extractelement <4 x float> zeroinitializer, i32 %idx2
; Split the array but don't replace the memset with an insert
; element as its not a constant offset.
; The load, however, can be replaced with an extract element.
define float @test1(i32 %idx1, i32 %idx2) {
entry:
%0 = alloca [4 x <4 x float>]
store [4 x <4 x float>] zeroinitializer, [4 x <4 x float>]* %0
%ptr1 = getelementptr [4 x <4 x float>]* %0, i32 0, i32 0, i32 %idx1
%cast = bitcast float* %ptr1 to i8*
call void @llvm.memset.p0i8.i32(i8* %cast, i8 0, i32 4, i32 4, i1 false)
%ptr2 = getelementptr [4 x <4 x float>]* %0, i32 0, i32 1, i32 %idx2
%ret = load float* %ptr2
ret float %ret
}
; CHECK: @test2
; CHECK: %[[ins:[\.a-z0-9]*]] = insertelement <4 x float> zeroinitializer, float 1.000000e+00, i32 %idx1
; CHECK: extractelement <4 x float> %[[ins]], i32 %idx2
; Do SROA on the array when it has dynamic vector reads and writes.
define float @test2(i32 %idx1, i32 %idx2) {
entry:
%0 = alloca [4 x <4 x float>]
store [4 x <4 x float>] zeroinitializer, [4 x <4 x float>]* %0
%ptr1 = getelementptr [4 x <4 x float>]* %0, i32 0, i32 0, i32 %idx1
store float 1.0, float* %ptr1
%ptr2 = getelementptr [4 x <4 x float>]* %0, i32 0, i32 0, i32 %idx2
%ret = load float* %ptr2
ret float %ret
}
; CHECK: test3
; CHECK: %0 = alloca [4 x <4 x float>]
; CHECK-NOT: alloca
; Don't do SROA on a dynamically indexed vector when it spans
; more than one array element of the alloca array it is within.
define float @test3(i32 %idx1, i32 %idx2) {
entry:
%0 = alloca [4 x <4 x float>]
store [4 x <4 x float>] zeroinitializer, [4 x <4 x float>]* %0
%bigvec = bitcast [4 x <4 x float>]* %0 to <16 x float>*
%ptr1 = getelementptr <16 x float>* %bigvec, i32 0, i32 %idx1
store float 1.0, float* %ptr1
%ptr2 = getelementptr <16 x float>* %bigvec, i32 0, i32 %idx2
%ret = load float* %ptr2
ret float %ret
}
; CHECK: test4
; CHECK: insertelement <16 x float> zeroinitializer, float 1.000000e+00, i32 %idx1
; CHECK: extractelement <16 x float> %0, i32 %idx2
; Don't do SROA on a dynamically indexed vector when it spans
; more than one array element of the alloca array it is within.
; However, unlike test3, the store is on the vector type
; so SROA will convert the large alloca into the large vector
; type and do all accesses with insert/extract element
define float @test4(i32 %idx1, i32 %idx2) {
entry:
%0 = alloca [4 x <4 x float>]
%bigvec = bitcast [4 x <4 x float>]* %0 to <16 x float>*
store <16 x float> zeroinitializer, <16 x float>* %bigvec
%ptr1 = getelementptr <16 x float>* %bigvec, i32 0, i32 %idx1
store float 1.0, float* %ptr1
%ptr2 = getelementptr <16 x float>* %bigvec, i32 0, i32 %idx2
%ret = load float* %ptr2
ret float %ret
}
; CHECK: @test5
; CHECK: %0 = alloca [4 x <4 x float>]
; CHECK-NOT: alloca
; Don't do SROA as the is a second dynamically indexed array
; which may span multiple elements of the alloca.
define float @test5(i32 %idx1, i32 %idx2) {
entry:
%0 = alloca [4 x <4 x float>]
store [4 x <4 x float>] zeroinitializer, [4 x <4 x float>]* %0
%ptr1 = getelementptr [4 x <4 x float>]* %0, i32 0, i32 0, i32 %idx1
%ptr2 = bitcast float* %ptr1 to [1 x <2 x float>]*
%ptr3 = getelementptr [1 x <2 x float>]* %ptr2, i32 0, i32 0, i32 %idx1
store float 1.0, float* %ptr1
%ptr4 = getelementptr [4 x <4 x float>]* %0, i32 0, i32 0, i32 %idx2
%ret = load float* %ptr4
ret float %ret
}
; CHECK: test6
; CHECK: insertelement <4 x float> zeroinitializer, float 1.000000e+00, i32 %idx1
; CHECK: extractelement <4 x float> zeroinitializer, i32 %idx2
%vector.pair = type { %vector.anon, %vector.anon }
%vector.anon = type { %vector }
%vector = type { <4 x float> }
; Dynamic GEPs on vectors were crashing when the vector was inside a struct
; as the new GEP for the new alloca might not include all the indices from
; the original GEP, just the indices it needs to get to the correct offset of
; some type, not necessarily the dynamic vector.
; This test makes sure we don't have this crash.
define float @test6(i32 %idx1, i32 %idx2) {
entry:
%0 = alloca %vector.pair
store %vector.pair zeroinitializer, %vector.pair* %0
%ptr1 = getelementptr %vector.pair* %0, i32 0, i32 0, i32 0, i32 0, i32 %idx1
store float 1.0, float* %ptr1
%ptr2 = getelementptr %vector.pair* %0, i32 0, i32 1, i32 0, i32 0, i32 %idx2
%ret = load float* %ptr2
ret float %ret
}
; CHECK: test7
; CHECK: insertelement <4 x float> zeroinitializer, float 1.000000e+00, i32 %idx1
; CHECK: extractelement <4 x float> zeroinitializer, i32 %idx2
%array.pair = type { [2 x %array.anon], %array.anon }
%array.anon = type { [2 x %vector] }
; This is the same as test6 and tests the same crash, but on arrays.
define float @test7(i32 %idx1, i32 %idx2) {
entry:
%0 = alloca %array.pair
store %array.pair zeroinitializer, %array.pair* %0
%ptr1 = getelementptr %array.pair* %0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 %idx1
store float 1.0, float* %ptr1
%ptr2 = getelementptr %array.pair* %0, i32 0, i32 1, i32 0, i32 0, i32 0, i32 %idx2
%ret = load float* %ptr2
ret float %ret
}
; CHECK: test8
; CHECK: %[[offset1:[\.a-z0-9]*]] = add i32 %idx1, 1
; CHECK: %[[ins:[\.a-z0-9]*]] = insertelement <4 x float> zeroinitializer, float 1.000000e+00, i32 %[[offset1]]
; CHECK: %[[offset2:[\.a-z0-9]*]] = add i32 %idx2, 2
; CHECK: extractelement <4 x float> %[[ins]], i32 %[[offset2]]
; Do SROA on the vector when it has dynamic vector reads and writes
; from a non-zero offset.
define float @test8(i32 %idx1, i32 %idx2) {
entry:
%0 = alloca <4 x float>
store <4 x float> zeroinitializer, <4 x float>* %0
%ptr1 = getelementptr <4 x float>* %0, i32 0, i32 1
%ptr2 = bitcast float* %ptr1 to <3 x float>*
%ptr3 = getelementptr <3 x float>* %ptr2, i32 0, i32 %idx1
store float 1.0, float* %ptr3
%ptr4 = getelementptr <4 x float>* %0, i32 0, i32 2
%ptr5 = bitcast float* %ptr4 to <2 x float>*
%ptr6 = getelementptr <2 x float>* %ptr5, i32 0, i32 %idx2
%ret = load float* %ptr6
ret float %ret
}
declare void @llvm.memset.p0i8.i32(i8*, i8, i32, i32, i1)