Commit 13a80eac authored by Jingyue Wu's avatar Jingyue Wu
Browse files

[SeparateConstOffsetFromGEP] strengthen the inbounds attribute 

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

llvm-svn: 244937
parent 65270736

llvm/lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp

+9 −4
Original line number Diff line number Diff line
@@ -892,12 +892,12 @@ bool SeparateConstOffsetFromGEP::splitGEP(GetElementPtrInst *GEP) { 
  // e.g.,

  //

  // b     = add i64 a, 5

  // addr = gep inbounds float* p, i64 b

  // 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
@@ -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.
@@ -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)
@@ -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);

  }

llvm/test/Transforms/SeparateConstOffsetFromGEP/AMDGPU/split-gep-and-gvn-addrspace-addressing-modes.ll

+7 −7
Original line number Diff line number Diff line
@@ -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
@@ -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]+}}
@@ -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

llvm/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/split-gep-and-gvn.ll

+12 −12
Original line number Diff line number Diff line
@@ -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
@@ -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
@@ -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
@@ -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

llvm/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/split-gep.ll

+8 −8
Original line number Diff line number Diff line
@@ -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)
@@ -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) {
@@ -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
@@ -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
@@ -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) {
@@ -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
@@ -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))",
@@ -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

llvm/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/value-tracking-domtree.ll

+1 −1
Original line number Diff line number Diff line
@@ -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: