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[SeparateConstOffsetFromGEP] strengthen the inbounds attribute
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We used to be over-conservative about preserving inbounds. Actually, the second
GEP (which applies the constant offset) can inherit the inbounds attribute of
the original GEP, because the resultant pointer is equivalent to that of the
original GEP. For example,

  x  = GEP inbounds a, i+5
    =>
  y = GEP a, i               // inbounds removed
  x = GEP inbounds y, 5      // inbounds preserved



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244937 91177308-0d34-0410-b5e6-96231b3b80d8
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Jingyue Wu committed Aug 13, 2015
1 parent 218b64b commit a49e110
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Showing 6 changed files with 39 additions and 34 deletions.
13 changes: 9 additions & 4 deletions lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -891,13 +891,13 @@ bool SeparateConstOffsetFromGEP::splitGEP(GetElementPtrInst *GEP) {
// Clear the inbounds attribute because the new index may be off-bound.
// e.g.,
//
// b = add i64 a, 5
// addr = gep inbounds float* p, i64 b
// b = add i64 a, 5
// addr = gep inbounds float, float* p, i64 b
//
// is transformed to:
//
// addr2 = gep float* p, i64 a
// addr = gep float* addr2, i64 5
// addr2 = gep float, float* p, i64 a ; inbounds removed
// addr = gep inbounds float, float* addr2, i64 5
//
// If a is -4, although the old index b is in bounds, the new index a is
// off-bound. http://llvm.org/docs/LangRef.html#id181 says "if the
Expand All @@ -907,6 +907,7 @@ bool SeparateConstOffsetFromGEP::splitGEP(GetElementPtrInst *GEP) {
//
// TODO(jingyue): do some range analysis to keep as many inbounds as
// possible. GEPs with inbounds are more friendly to alias analysis.
bool GEPWasInBounds = GEP->isInBounds();
GEP->setIsInBounds(false);

// Lowers a GEP to either GEPs with a single index or arithmetic operations.
Expand Down Expand Up @@ -968,6 +969,8 @@ bool SeparateConstOffsetFromGEP::splitGEP(GetElementPtrInst *GEP) {
NewGEP = GetElementPtrInst::Create(GEP->getResultElementType(), NewGEP,
ConstantInt::get(IntPtrTy, Index, true),
GEP->getName(), GEP);
// Inherit the inbounds attribute of the original GEP.
cast<GetElementPtrInst>(NewGEP)->setIsInBounds(GEPWasInBounds);
} else {
// Unlikely but possible. For example,
// #pragma pack(1)
Expand All @@ -990,6 +993,8 @@ bool SeparateConstOffsetFromGEP::splitGEP(GetElementPtrInst *GEP) {
Type::getInt8Ty(GEP->getContext()), NewGEP,
ConstantInt::get(IntPtrTy, AccumulativeByteOffset, true), "uglygep",
GEP);
// Inherit the inbounds attribute of the original GEP.
cast<GetElementPtrInst>(NewGEP)->setIsInBounds(GEPWasInBounds);
if (GEP->getType() != I8PtrTy)
NewGEP = new BitCastInst(NewGEP, GEP->getType(), GEP->getName(), GEP);
}
Expand Down
14 changes: 7 additions & 7 deletions ...nsforms/SeparateConstOffsetFromGEP/AMDGPU/split-gep-and-gvn-addrspace-addressing-modes.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,9 @@ target datalayout = "e-p:32:32-p1:64:64-p2:64:64-p3:32:32-p4:64:64-p5:32:32-p24:

; IR-LABEL: @sum_of_array(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr inbounds [4096 x [32 x float]], [4096 x [32 x float]] addrspace(2)* @array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr float, float addrspace(2)* [[BASE_PTR]], i64 1
; IR: getelementptr float, float addrspace(2)* [[BASE_PTR]], i64 32
; IR: getelementptr float, float addrspace(2)* [[BASE_PTR]], i64 33
; IR: getelementptr inbounds float, float addrspace(2)* [[BASE_PTR]], i64 1
; IR: getelementptr inbounds float, float addrspace(2)* [[BASE_PTR]], i64 32
; IR: getelementptr inbounds float, float addrspace(2)* [[BASE_PTR]], i64 33
define void @sum_of_array(i32 %x, i32 %y, float addrspace(1)* nocapture %output) {
%tmp = sext i32 %y to i64
%tmp1 = sext i32 %x to i64
Expand Down Expand Up @@ -38,7 +38,7 @@ define void @sum_of_array(i32 %x, i32 %y, float addrspace(1)* nocapture %output)

; IR-LABEL: @sum_of_array_over_max_mubuf_offset(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr inbounds [4096 x [4 x float]], [4096 x [4 x float]] addrspace(2)* @array2, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr float, float addrspace(2)* [[BASE_PTR]], i64 255
; IR: getelementptr inbounds float, float addrspace(2)* [[BASE_PTR]], i64 255
; IR: add i32 %x, 256
; IR: getelementptr inbounds [4096 x [4 x float]], [4096 x [4 x float]] addrspace(2)* @array2, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr inbounds [4096 x [4 x float]], [4096 x [4 x float]] addrspace(2)* @array2, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
Expand Down Expand Up @@ -71,9 +71,9 @@ define void @sum_of_array_over_max_mubuf_offset(i32 %x, i32 %y, float addrspace(
; DS instructions have a larger immediate offset, so make sure these are OK.
; IR-LABEL: @sum_of_lds_array_over_max_mubuf_offset(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr inbounds [4096 x [4 x float]], [4096 x [4 x float]] addrspace(3)* @lds_array, i32 0, i32 %{{[a-zA-Z0-9]+}}, i32 %{{[a-zA-Z0-9]+}}
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i32 255
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i32 16128
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i32 16383
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i32 255
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i32 16128
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i32 16383
define void @sum_of_lds_array_over_max_mubuf_offset(i32 %x, i32 %y, float addrspace(1)* nocapture %output) {
%tmp2 = getelementptr inbounds [4096 x [4 x float]], [4096 x [4 x float]] addrspace(3)* @lds_array, i32 0, i32 %x, i32 %y
%tmp4 = load float, float addrspace(3)* %tmp2, align 4
Expand Down
24 changes: 12 additions & 12 deletions test/Transforms/SeparateConstOffsetFromGEP/NVPTX/split-gep-and-gvn.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -52,9 +52,9 @@ define void @sum_of_array(i32 %x, i32 %y, float* nocapture %output) {

; IR-LABEL: @sum_of_array(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 33
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 33

; @sum_of_array2 is very similar to @sum_of_array. The only difference is in
; the order of "sext" and "add" when computing the array indices. @sum_of_array
Expand Down Expand Up @@ -95,9 +95,9 @@ define void @sum_of_array2(i32 %x, i32 %y, float* nocapture %output) {

; IR-LABEL: @sum_of_array2(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 33
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 33


; This function loads
Expand Down Expand Up @@ -145,9 +145,9 @@ define void @sum_of_array3(i32 %x, i32 %y, float* nocapture %output) {

; IR-LABEL: @sum_of_array3(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 33
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 33


; This function loads
Expand Down Expand Up @@ -191,6 +191,6 @@ define void @sum_of_array4(i32 %x, i32 %y, float* nocapture %output) {

; IR-LABEL: @sum_of_array4(
; IR: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr inbounds [32 x [32 x float]], [32 x [32 x float]] addrspace(3)* @array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr float, float addrspace(3)* [[BASE_PTR]], i64 33
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 1
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 32
; IR: getelementptr inbounds float, float addrspace(3)* [[BASE_PTR]], i64 33
16 changes: 8 additions & 8 deletions test/Transforms/SeparateConstOffsetFromGEP/NVPTX/split-gep.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,7 @@ entry:
; CHECK: add i32 %j, -2
; CHECK: sext
; CHECK: getelementptr [32 x [32 x float]], [32 x [32 x float]]* @float_2d_array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; CHECK: getelementptr float, float* %{{[a-zA-Z0-9]+}}, i64 32
; CHECK: getelementptr inbounds float, float* %{{[a-zA-Z0-9]+}}, i64 32

; We should be able to trace into sext/zext if it can be distributed to both
; operands, e.g., sext (add nsw a, b) == add nsw (sext a), (sext b)
Expand All @@ -65,7 +65,7 @@ define float* @ext_add_no_overflow(i64 %a, i32 %b, i64 %c, i32 %d) {
}
; CHECK-LABEL: @ext_add_no_overflow(
; CHECK: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr [32 x [32 x float]], [32 x [32 x float]]* @float_2d_array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; CHECK: getelementptr float, float* [[BASE_PTR]], i64 33
; CHECK: getelementptr inbounds float, float* [[BASE_PTR]], i64 33

; Verifies we handle nested sext/zext correctly.
define void @sext_zext(i32 %a, i32 %b, float** %out1, float** %out2) {
Expand Down Expand Up @@ -110,7 +110,7 @@ entry:
}
; CHECK-LABEL: @sext_or(
; CHECK: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr [32 x [32 x float]], [32 x [32 x float]]* @float_2d_array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 %{{[a-zA-Z0-9]+}}
; CHECK: getelementptr float, float* [[BASE_PTR]], i64 32
; CHECK: getelementptr inbounds float, float* [[BASE_PTR]], i64 32

; The subexpression (b + 5) is used in both "i = a + (b + 5)" and "*out = b +
; 5". When extracting the constant offset 5, make sure "*out = b + 5" isn't
Expand All @@ -125,7 +125,7 @@ entry:
}
; CHECK-LABEL: @expr(
; CHECK: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr [32 x [32 x float]], [32 x [32 x float]]* @float_2d_array, i64 0, i64 %{{[a-zA-Z0-9]+}}, i64 0
; CHECK: getelementptr float, float* [[BASE_PTR]], i64 160
; CHECK: getelementptr inbounds float, float* [[BASE_PTR]], i64 160
; CHECK: store i64 %b5, i64* %out

; d + sext(a +nsw (b +nsw (c +nsw 8))) => (d + sext(a) + sext(b) + sext(c)) + 8
Expand All @@ -143,7 +143,7 @@ entry:
; CHECK: sext i32
; CHECK: sext i32
; CHECK: sext i32
; CHECK: getelementptr float, float* %{{[a-zA-Z0-9]+}}, i64 8
; CHECK: getelementptr inbounds float, float* %{{[a-zA-Z0-9]+}}, i64 8

; Verifies we handle "sub" correctly.
define float* @sub(i64 %i, i64 %j) {
Expand All @@ -155,7 +155,7 @@ define float* @sub(i64 %i, i64 %j) {
; CHECK-LABEL: @sub(
; CHECK: %[[j2:[a-zA-Z0-9]+]] = sub i64 0, %j
; CHECK: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr [32 x [32 x float]], [32 x [32 x float]]* @float_2d_array, i64 0, i64 %i, i64 %[[j2]]
; CHECK: getelementptr float, float* [[BASE_PTR]], i64 -155
; CHECK: getelementptr inbounds float, float* [[BASE_PTR]], i64 -155

%struct.Packed = type <{ [3 x i32], [8 x i64] }> ; <> means packed

Expand All @@ -173,7 +173,7 @@ entry:
; CHECK-LABEL: @packed_struct(
; CHECK: [[BASE_PTR:%[a-zA-Z0-9]+]] = getelementptr [1024 x %struct.Packed], [1024 x %struct.Packed]* %s, i64 0, i64 %{{[a-zA-Z0-9]+}}, i32 1, i64 %{{[a-zA-Z0-9]+}}
; CHECK: [[CASTED_PTR:%[a-zA-Z0-9]+]] = bitcast i64* [[BASE_PTR]] to i8*
; CHECK: %uglygep = getelementptr i8, i8* [[CASTED_PTR]], i64 100
; CHECK: %uglygep = getelementptr inbounds i8, i8* [[CASTED_PTR]], i64 100
; CHECK: bitcast i8* %uglygep to i64*

; We shouldn't be able to extract the 8 from "zext(a +nuw (b + 8))",
Expand Down Expand Up @@ -272,7 +272,7 @@ entry:
%ptr2 = getelementptr inbounds %struct0, %struct0* %ptr, i64 0, i32 3, i64 %arrayidx, i32 1
; CHECK: [[PTR:%[a-zA-Z0-9]+]] = getelementptr %struct0, %struct0* %ptr, i64 0, i32 3, i64 %idx, i32 1
; CHECK: [[PTR1:%[a-zA-Z0-9]+]] = bitcast %struct2* [[PTR]] to i8*
; CHECK: getelementptr i8, i8* [[PTR1]], i64 -64
; CHECK: getelementptr inbounds i8, i8* [[PTR1]], i64 -64
; CHECK: bitcast
ret %struct2* %ptr2
; CHECK-NEXT: ret
Expand Down
2 changes: 1 addition & 1 deletion test/Transforms/SeparateConstOffsetFromGEP/NVPTX/value-tracking-domtree.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,7 @@ then:
%or = or i64 %i, 3
%p = getelementptr inbounds float, float* %input, i64 %or
; CHECK: [[base:[^ ]+]] = getelementptr float, float* %input, i64 %i
; CHECK: getelementptr float, float* [[base]], i64 3
; CHECK: getelementptr inbounds float, float* [[base]], i64 3
ret float* %p

exit:
Expand Down
4 changes: 2 additions & 2 deletions test/Transforms/StraightLineStrengthReduce/AMDGPU/reassociate-geps-and-slsr-addrspace.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -57,10 +57,10 @@ bb:

; CHECK-LABEL: @slsr_after_reassociate_lds_geps_ds_max_offset(
; CHECK: [[B1:%[0-9]+]] = getelementptr float, float addrspace(3)* %arr, i32 %i
; CHECK: getelementptr float, float addrspace(3)* [[B1]], i32 16383
; CHECK: getelementptr inbounds float, float addrspace(3)* [[B1]], i32 16383

; CHECK: [[B2:%[0-9]+]] = getelementptr float, float addrspace(3)* [[B1]], i32 %i
; CHECK: getelementptr float, float addrspace(3)* [[B2]], i32 16383
; CHECK: getelementptr inbounds float, float addrspace(3)* [[B2]], i32 16383
define void @slsr_after_reassociate_lds_geps_ds_max_offset(float addrspace(1)* %out, float addrspace(3)* noalias %arr, i32 %i) {
bb:
%i2 = shl nsw i32 %i, 1
Expand Down

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