Unverified Commit 6d667d4b authored by Yingwei Zheng's avatar Yingwei Zheng
Browse files

[InstCombine] Combine const GEP chains 

This patch reverts rGae739aefd7473517d3f08b5c8d08a66c7f469198 to address performance regressions reported by our [CI](https://github.com/dtcxzyw/llvm-ci/issues/137) after rG2ec1d0f427c7822540352c0c14d057e7bfe4f77b.

For example:
```
define ptr @const_gep_chain(ptr %p, i64 %a) {
    %p1 = getelementptr inbounds i8, ptr %p, i64 %a
    %p2 = getelementptr inbounds i8, ptr %p1, i64 1
    %p3 = getelementptr inbounds i8, ptr %p2, i64 2
    %p4 = getelementptr inbounds i8, ptr %p3, i64 3
    ret ptr %p4
}
```
The last three GEPs will not be folded since rG2ec1d0f427c7822540352c0c14d057e7bfe4f77b.

I think it is appropriate to remove this code because there is no compile-time regression reported in our benchmarks.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D149240
parent da0089c9

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

+0 −7
Original line number Diff line number Diff line
@@ -1950,13 +1950,6 @@ Instruction *InstCombinerImpl::visitGEPOfGEP(GetElementPtrInst &GEP, 
  if (!shouldMergeGEPs(*cast<GEPOperator>(&GEP), *Src))

    return nullptr;



  // Note that if our source is a gep chain itself then we wait for that

  // chain to be resolved before we perform this transformation.  This

  // avoids us creating a TON of code in some cases.

  if (auto *SrcGEP = dyn_cast<GEPOperator>(Src->getOperand(0)))

    if (SrcGEP->getNumOperands() == 2 && shouldMergeGEPs(*Src, *SrcGEP))

      return nullptr;   // Wait until our source is folded to completion.



  // For constant GEPs, use a more general offset-based folding approach.

  Type *PtrTy = Src->getType()->getScalarType();

  if (GEP.hasAllConstantIndices() &&

llvm/test/Transforms/InstCombine/getelementptr.ll

+13 −0
Original line number Diff line number Diff line
@@ -1389,4 +1389,17 @@ define ptr @const_gep_0xi8_global() { 
  ret ptr getelementptr ([0 x i8], ptr @g_0xi8_e, i64 0, i64 10)

}



define ptr @const_gep_chain(ptr %p, i64 %a) {

; CHECK-LABEL: @const_gep_chain(

; CHECK-NEXT:    [[P1:%.*]] = getelementptr inbounds i8, ptr [[P:%.*]], i64 [[A:%.*]]

; CHECK-NEXT:    [[P4:%.*]] = getelementptr inbounds i8, ptr [[P1]], i64 6

; CHECK-NEXT:    ret ptr [[P4]]

;

  %p1 = getelementptr inbounds i8, ptr %p, i64 %a

  %p2 = getelementptr inbounds i8, ptr %p1, i64 1

  %p3 = getelementptr inbounds i8, ptr %p2, i64 2

  %p4 = getelementptr inbounds i8, ptr %p3, i64 3

  ret ptr %p4

}



!0 = !{!"branch_weights", i32 2, i32 10}

llvm/test/Transforms/LoopVectorize/AArch64/vector-reverse-mask4.ll

+22 −24
Original line number Diff line number Diff line
@@ -37,27 +37,25 @@ define void @vector_reverse_mask_v4i1(ptr noalias %a, ptr noalias %cond, i64 %N) 
; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds double, ptr [[TMP2]], i64 -3

; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <4 x double>, ptr [[TMP3]], align 8

; CHECK-NEXT:    [[REVERSE:%.*]] = shufflevector <4 x double> [[WIDE_LOAD]], <4 x double> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>

; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds double, ptr [[TMP2]], i64 -4

; CHECK-NEXT:    [[TMP6:%.*]] = getelementptr inbounds double, ptr [[TMP5]], i64 -3

; CHECK-NEXT:    [[WIDE_LOAD1:%.*]] = load <4 x double>, ptr [[TMP6]], align 8

; CHECK-NEXT:    [[TMP4:%.*]] = getelementptr inbounds double, ptr [[TMP2]], i64 -7

; CHECK-NEXT:    [[WIDE_LOAD1:%.*]] = load <4 x double>, ptr [[TMP4]], align 8

; CHECK-NEXT:    [[REVERSE2:%.*]] = shufflevector <4 x double> [[WIDE_LOAD1]], <4 x double> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>

; CHECK-NEXT:    [[TMP8:%.*]] = fcmp une <4 x double> [[REVERSE]], zeroinitializer

; CHECK-NEXT:    [[TMP9:%.*]] = fcmp une <4 x double> [[REVERSE2]], zeroinitializer

; CHECK-NEXT:    [[TMP10:%.*]] = getelementptr double, ptr [[A:%.*]], i64 [[TMP1]]

; CHECK-NEXT:    [[TMP11:%.*]] = getelementptr double, ptr [[TMP10]], i64 -3

; CHECK-NEXT:    [[REVERSE3:%.*]] = shufflevector <4 x i1> [[TMP8]], <4 x i1> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>

; CHECK-NEXT:    [[WIDE_MASKED_LOAD:%.*]] = call <4 x double> @llvm.masked.load.v4f64.p0(ptr [[TMP11]], i32 8, <4 x i1> [[REVERSE3]], <4 x double> poison)

; CHECK-NEXT:    [[TMP13:%.*]] = getelementptr double, ptr [[TMP10]], i64 -4

; CHECK-NEXT:    [[TMP14:%.*]] = getelementptr double, ptr [[TMP13]], i64 -3

; CHECK-NEXT:    [[REVERSE5:%.*]] = shufflevector <4 x i1> [[TMP9]], <4 x i1> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>

; CHECK-NEXT:    [[WIDE_MASKED_LOAD6:%.*]] = call <4 x double> @llvm.masked.load.v4f64.p0(ptr [[TMP14]], i32 8, <4 x i1> [[REVERSE5]], <4 x double> poison)

; CHECK-NEXT:    [[TMP16:%.*]] = fadd <4 x double> [[WIDE_MASKED_LOAD]], <double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00>

; CHECK-NEXT:    [[TMP17:%.*]] = fadd <4 x double> [[WIDE_MASKED_LOAD6]], <double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00>

; CHECK-NEXT:    call void @llvm.masked.store.v4f64.p0(<4 x double> [[TMP16]], ptr [[TMP11]], i32 8, <4 x i1> [[REVERSE3]])

; CHECK-NEXT:    call void @llvm.masked.store.v4f64.p0(<4 x double> [[TMP17]], ptr [[TMP14]], i32 8, <4 x i1> [[REVERSE5]])

; CHECK-NEXT:    [[TMP5:%.*]] = fcmp une <4 x double> [[REVERSE]], zeroinitializer

; CHECK-NEXT:    [[TMP6:%.*]] = fcmp une <4 x double> [[REVERSE2]], zeroinitializer

; CHECK-NEXT:    [[TMP7:%.*]] = getelementptr double, ptr [[A:%.*]], i64 [[TMP1]]

; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr double, ptr [[TMP7]], i64 -3

; CHECK-NEXT:    [[REVERSE3:%.*]] = shufflevector <4 x i1> [[TMP5]], <4 x i1> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>

; CHECK-NEXT:    [[WIDE_MASKED_LOAD:%.*]] = call <4 x double> @llvm.masked.load.v4f64.p0(ptr [[TMP8]], i32 8, <4 x i1> [[REVERSE3]], <4 x double> poison)

; CHECK-NEXT:    [[TMP9:%.*]] = getelementptr double, ptr [[TMP7]], i64 -7

; CHECK-NEXT:    [[REVERSE5:%.*]] = shufflevector <4 x i1> [[TMP6]], <4 x i1> poison, <4 x i32> <i32 3, i32 2, i32 1, i32 0>

; CHECK-NEXT:    [[WIDE_MASKED_LOAD6:%.*]] = call <4 x double> @llvm.masked.load.v4f64.p0(ptr [[TMP9]], i32 8, <4 x i1> [[REVERSE5]], <4 x double> poison)

; CHECK-NEXT:    [[TMP10:%.*]] = fadd <4 x double> [[WIDE_MASKED_LOAD]], <double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00>

; CHECK-NEXT:    [[TMP11:%.*]] = fadd <4 x double> [[WIDE_MASKED_LOAD6]], <double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00>

; CHECK-NEXT:    call void @llvm.masked.store.v4f64.p0(<4 x double> [[TMP10]], ptr [[TMP8]], i32 8, <4 x i1> [[REVERSE3]])

; CHECK-NEXT:    call void @llvm.masked.store.v4f64.p0(<4 x double> [[TMP11]], ptr [[TMP9]], i32 8, <4 x i1> [[REVERSE5]])

; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 8

; CHECK-NEXT:    [[TMP20:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]

; CHECK-NEXT:    br i1 [[TMP20]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]

; CHECK-NEXT:    [[TMP12:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]

; CHECK-NEXT:    br i1 [[TMP12]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]

; CHECK:       middle.block:

; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i64 [[N_VEC]], [[N]]

; CHECK-NEXT:    br i1 [[CMP_N]], label [[FOR_COND_CLEANUP_LOOPEXIT:%.*]], label [[SCALAR_PH]]
@@ -72,18 +70,18 @@ define void @vector_reverse_mask_v4i1(ptr noalias %a, ptr noalias %cond, i64 %N) 
; CHECK-NEXT:    [[I_08_IN:%.*]] = phi i64 [ [[I_08:%.*]], [[FOR_INC:%.*]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]

; CHECK-NEXT:    [[I_08]] = add nsw i64 [[I_08_IN]], -1

; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds double, ptr [[COND]], i64 [[I_08]]

; CHECK-NEXT:    [[TMP21:%.*]] = load double, ptr [[ARRAYIDX]], align 8

; CHECK-NEXT:    [[TOBOOL:%.*]] = fcmp une double [[TMP21]], 0.000000e+00

; CHECK-NEXT:    [[TMP13:%.*]] = load double, ptr [[ARRAYIDX]], align 8

; CHECK-NEXT:    [[TOBOOL:%.*]] = fcmp une double [[TMP13]], 0.000000e+00

; CHECK-NEXT:    br i1 [[TOBOOL]], label [[IF_THEN:%.*]], label [[FOR_INC]]

; CHECK:       if.then:

; CHECK-NEXT:    [[ARRAYIDX1:%.*]] = getelementptr inbounds double, ptr [[A]], i64 [[I_08]]

; CHECK-NEXT:    [[TMP22:%.*]] = load double, ptr [[ARRAYIDX1]], align 8

; CHECK-NEXT:    [[ADD:%.*]] = fadd double [[TMP22]], 1.000000e+00

; CHECK-NEXT:    [[TMP14:%.*]] = load double, ptr [[ARRAYIDX1]], align 8

; CHECK-NEXT:    [[ADD:%.*]] = fadd double [[TMP14]], 1.000000e+00

; CHECK-NEXT:    store double [[ADD]], ptr [[ARRAYIDX1]], align 8

; CHECK-NEXT:    br label [[FOR_INC]]

; CHECK:       for.inc:

; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i64 [[I_08_IN]], 1

; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_COND_CLEANUP_LOOPEXIT]], !llvm.loop [[LOOP3:![0-9]+]]

; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_COND_CLEANUP_LOOPEXIT]], !llvm.loop [[LOOP4:![0-9]+]]

;



entry:

llvm/test/Transforms/LoopVectorize/consecutive-ptr-uniforms.ll

+5 −7
Original line number Diff line number Diff line
@@ -450,14 +450,12 @@ for.end: 
; INTER:       vector.body:

; INTER-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %vector.ph ], [ [[INDEX_NEXT:%.*]], %vector.body ]

; INTER-NEXT:    [[TMP4:%.*]] = getelementptr inbounds i64, ptr %A, i64 [[INDEX]]

; INTER-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[TMP4]], i64 3

; INTER-NEXT:    [[TMP6:%.*]] = getelementptr inbounds i8, ptr [[TMP5]], i64 -3

; INTER-NEXT:    [[WIDE_VEC:%.*]] = load <32 x i8>, ptr [[TMP6]], align 1

; INTER-NEXT:    [[WIDE_VEC:%.*]] = load <32 x i8>, ptr [[TMP4]], align 1

; INTER-NEXT:    [[STRIDED_VEC:%.*]] = shufflevector <32 x i8> [[WIDE_VEC]], <32 x i8> poison, <4 x i32> <i32 0, i32 8, i32 16, i32 24>

; INTER-NEXT:    [[STRIDED_VEC5:%.*]] = shufflevector <32 x i8> [[WIDE_VEC]], <32 x i8> poison, <4 x i32> <i32 3, i32 11, i32 19, i32 27>

; INTER-NEXT:    [[TMP6:%.*]] = xor <4 x i8> [[STRIDED_VEC5]], [[STRIDED_VEC]]

; INTER-NEXT:    [[TMP7:%.*]] = getelementptr inbounds i8, ptr %B, i64 [[INDEX]]

; INTER-NEXT:    store <4 x i8> [[TMP6]], ptr [[TMP7]], align 1

; INTER-NEXT:    [[STRIDED_VEC3:%.*]] = shufflevector <32 x i8> [[WIDE_VEC]], <32 x i8> poison, <4 x i32> <i32 3, i32 11, i32 19, i32 27>

; INTER-NEXT:    [[TMP5:%.*]] = xor <4 x i8> [[STRIDED_VEC3]], [[STRIDED_VEC]]

; INTER-NEXT:    [[TMP6:%.*]] = getelementptr inbounds i8, ptr %B, i64 [[INDEX]]

; INTER-NEXT:    store <4 x i8> [[TMP5]], ptr [[TMP6]], align 1

; INTER-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4

; INTER:         br i1 {{.*}}, label %middle.block, label %vector.body

;

llvm/test/Transforms/LoopVectorize/interleaved-accesses.ll

+8 −10
Original line number Diff line number Diff line
@@ -745,18 +745,16 @@ define void @mixed_load3_store3(ptr nocapture %A) { 
; CHECK-NEXT:    [[STRIDED_VEC2:%.*]] = shufflevector <12 x i32> [[WIDE_VEC]], <12 x i32> poison, <4 x i32> <i32 1, i32 4, i32 7, i32 10>

; CHECK-NEXT:    [[STRIDED_VEC3:%.*]] = shufflevector <12 x i32> [[WIDE_VEC]], <12 x i32> poison, <4 x i32> <i32 2, i32 5, i32 8, i32 11>

; CHECK-NEXT:    [[TMP1:%.*]] = add <4 x i32> [[STRIDED_VEC]], [[VEC_IND]]

; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds i32, ptr [[NEXT_GEP]], i64 2

; CHECK-NEXT:    [[TMP3:%.*]] = add <4 x i32> [[STRIDED_VEC2]], [[VEC_IND]]

; CHECK-NEXT:    [[TMP4:%.*]] = add <4 x i32> [[STRIDED_VEC3]], [[VEC_IND]]

; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i32, ptr [[TMP2]], i64 -2

; CHECK-NEXT:    [[TMP6:%.*]] = shufflevector <4 x i32> [[TMP1]], <4 x i32> [[TMP3]], <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>

; CHECK-NEXT:    [[TMP7:%.*]] = shufflevector <4 x i32> [[TMP4]], <4 x i32> poison, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison>

; CHECK-NEXT:    [[INTERLEAVED_VEC:%.*]] = shufflevector <8 x i32> [[TMP6]], <8 x i32> [[TMP7]], <12 x i32> <i32 0, i32 4, i32 8, i32 1, i32 5, i32 9, i32 2, i32 6, i32 10, i32 3, i32 7, i32 11>

; CHECK-NEXT:    store <12 x i32> [[INTERLEAVED_VEC]], ptr [[TMP5]], align 4

; CHECK-NEXT:    [[TMP2:%.*]] = add <4 x i32> [[STRIDED_VEC2]], [[VEC_IND]]

; CHECK-NEXT:    [[TMP3:%.*]] = add <4 x i32> [[STRIDED_VEC3]], [[VEC_IND]]

; CHECK-NEXT:    [[TMP4:%.*]] = shufflevector <4 x i32> [[TMP1]], <4 x i32> [[TMP2]], <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7>

; CHECK-NEXT:    [[TMP5:%.*]] = shufflevector <4 x i32> [[TMP3]], <4 x i32> poison, <8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 poison, i32 poison, i32 poison, i32 poison>

; CHECK-NEXT:    [[INTERLEAVED_VEC:%.*]] = shufflevector <8 x i32> [[TMP4]], <8 x i32> [[TMP5]], <12 x i32> <i32 0, i32 4, i32 8, i32 1, i32 5, i32 9, i32 2, i32 6, i32 10, i32 3, i32 7, i32 11>

; CHECK-NEXT:    store <12 x i32> [[INTERLEAVED_VEC]], ptr [[NEXT_GEP]], align 4

; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4

; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <4 x i32> [[VEC_IND]], <i32 4, i32 4, i32 4, i32 4>

; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i64 [[INDEX_NEXT]], 1024

; CHECK-NEXT:    br i1 [[TMP8]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP20:![0-9]+]]

; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i64 [[INDEX_NEXT]], 1024

; CHECK-NEXT:    br i1 [[TMP6]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP20:![0-9]+]]

; CHECK:       middle.block:

; CHECK-NEXT:    br i1 true, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]

; CHECK:       scalar.ph: