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llvm-project/llvm/test/Transforms/LoopVectorize/loop-scalars.ll
Peter Collingbourne b3c54914ef
InstCombine: Stop transforming EQ/NE of SHR to 0 to ULT/UGT if >1 use 
This is a small code size optimization that lets us avoid both shifting
and comparing to a constant if we need the shifted value anyway. On most
architectures the zero comparison is cheaper than a constant comparison
(or free if the shift sets flags).

Although this change appears to remove the optimization entirely, we
continue to do this transform if there is one use because of the code
below the removed code that transforms the shift into an and, followed
by the PR10267 case in InstCombinerImpl::foldICmpAndConstConst that
transforms the and into a ult/ugt. Added a test case to verify this
explicitly.

Per [1] reduces clang .text size by 0.09% and dynamic instruction count
by 0.01%.

[1] https://llvm-compile-time-tracker.com/compare.php?from=1f38d49ebe96417e368a567efa4d650b8a9ac30f&to=0873787a12b8f2eab019d8211ace4bccc1807343&stat=size-text

Reviewers: nikic, dtcxzyw

Reviewed By: dtcxzyw

Pull Request: https://github.com/llvm/llvm-project/pull/168007
2025-11-17 19:39:20 -08:00

233 lines
11 KiB
LLVM
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; REQUIRES: asserts
; RUN: opt < %s -aa-pipeline=basic-aa -passes=loop-vectorize,instcombine -force-vector-width=2 -force-vector-interleave=1 -debug-only=loop-vectorize -disable-output -print-after=instcombine 2>&1 | FileCheck %s
target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
;
define void @vector_gep(ptr %a, ptr %b, i64 %n) {
; CHECK-LABEL: @vector_gep(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SMAX:%.*]] = call i64 @llvm.smax.i64(i64 [[N:%.*]], i64 1)
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp slt i64 [[N]], 2
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_VEC:%.*]] = and i64 [[SMAX]], 9223372036854775806
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[VEC_IND:%.*]] = phi <2 x i64> [ <i64 0, i64 1>, [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds i32, ptr [[B:%.*]], <2 x i64> [[VEC_IND]]
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds ptr, ptr [[A:%.*]], i64 [[INDEX]]
; CHECK-NEXT: store <2 x ptr> [[TMP0]], ptr [[TMP1]], align 8
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
; CHECK-NEXT: [[VEC_IND_NEXT]] = add nuw nsw <2 x i64> [[VEC_IND]], splat (i64 2)
; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP2]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[SMAX]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[I:%.*]] = phi i64 [ [[I_NEXT:%.*]], [[FOR_BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[VAR0:%.*]] = getelementptr inbounds nuw i32, ptr [[B]], i64 [[I]]
; CHECK-NEXT: [[VAR1:%.*]] = getelementptr inbounds nuw ptr, ptr [[A]], i64 [[I]]
; CHECK-NEXT: store ptr [[VAR0]], ptr [[VAR1]], align 8
; CHECK-NEXT: [[I_NEXT]] = add nuw nsw i64 [[I]], 1
; CHECK-NEXT: [[COND:%.*]] = icmp slt i64 [[I_NEXT]], [[N]]
; CHECK-NEXT: br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END]], !llvm.loop [[LOOP3:![0-9]+]]
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
br label %for.body
for.body:
%i = phi i64 [ %i.next, %for.body ], [ 0, %entry ]
%var0 = getelementptr inbounds i32, ptr %b, i64 %i
%var1 = getelementptr inbounds ptr, ptr %a, i64 %i
store ptr %var0, ptr %var1, align 8
%i.next = add nuw nsw i64 %i, 1
%cond = icmp slt i64 %i.next, %n
br i1 %cond, label %for.body, label %for.end
for.end:
ret void
}
;
define void @scalar_store(ptr %a, ptr %b, i64 %n) {
; CHECK-LABEL: @scalar_store(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SMAX:%.*]] = call i64 @llvm.smax.i64(i64 [[N:%.*]], i64 2)
; CHECK-NEXT: [[TMP0:%.*]] = add nsw i64 [[SMAX]], -1
; CHECK-NEXT: [[TMP1:%.*]] = lshr i64 [[TMP0]], 1
; CHECK-NEXT: [[TMP2:%.*]] = add nuw nsw i64 [[TMP1]], 1
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp eq i64 [[TMP1]], 0
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_VEC:%.*]] = and i64 [[TMP2]], 9223372036854775806
; CHECK-NEXT: [[IND_END:%.*]] = shl nuw i64 [[N_VEC]], 1
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[OFFSET_IDX:%.*]] = shl i64 [[INDEX]], 1
; CHECK-NEXT: [[TMP3:%.*]] = or disjoint i64 [[OFFSET_IDX]], 2
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds i32, ptr [[B:%.*]], i64 [[OFFSET_IDX]]
; CHECK-NEXT: [[TMP5:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[TMP3]]
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr inbounds ptr, ptr [[A:%.*]], i64 [[OFFSET_IDX]]
; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds ptr, ptr [[A]], i64 [[TMP3]]
; CHECK-NEXT: store ptr [[TMP4]], ptr [[TMP6]], align 8
; CHECK-NEXT: store ptr [[TMP5]], ptr [[TMP7]], align 8
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
; CHECK-NEXT: [[TMP8:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP8]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[TMP2]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[IND_END]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[I:%.*]] = phi i64 [ [[I_NEXT:%.*]], [[FOR_BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[VAR0:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[I]]
; CHECK-NEXT: [[VAR1:%.*]] = getelementptr inbounds ptr, ptr [[A]], i64 [[I]]
; CHECK-NEXT: store ptr [[VAR0]], ptr [[VAR1]], align 8
; CHECK-NEXT: [[I_NEXT]] = add nuw nsw i64 [[I]], 2
; CHECK-NEXT: [[COND:%.*]] = icmp slt i64 [[I_NEXT]], [[N]]
; CHECK-NEXT: br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END]], !llvm.loop [[LOOP5:![0-9]+]]
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
br label %for.body
for.body:
%i = phi i64 [ %i.next, %for.body ], [ 0, %entry ]
%var0 = getelementptr inbounds i32, ptr %b, i64 %i
%var1 = getelementptr inbounds ptr, ptr %a, i64 %i
store ptr %var0, ptr %var1, align 8
%i.next = add nuw nsw i64 %i, 2
%cond = icmp slt i64 %i.next, %n
br i1 %cond, label %for.body, label %for.end
for.end:
ret void
}
;
define void @expansion(ptr %a, ptr %b, i64 %n) {
; CHECK-LABEL: @expansion(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SMAX:%.*]] = call i64 @llvm.smax.i64(i64 [[N:%.*]], i64 2)
; CHECK-NEXT: [[TMP0:%.*]] = add nsw i64 [[SMAX]], -1
; CHECK-NEXT: [[TMP1:%.*]] = lshr i64 [[TMP0]], 1
; CHECK-NEXT: [[TMP2:%.*]] = add nuw nsw i64 [[TMP1]], 1
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp eq i64 [[TMP1]], 0
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_VEC:%.*]] = and i64 [[TMP2]], 9223372036854775806
; CHECK-NEXT: [[IND_END:%.*]] = shl nuw i64 [[N_VEC]], 1
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[OFFSET_IDX:%.*]] = shl i64 [[INDEX]], 1
; CHECK-NEXT: [[TMP3:%.*]] = or disjoint i64 [[OFFSET_IDX]], 2
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds i64, ptr [[B:%.*]], i64 [[OFFSET_IDX]]
; CHECK-NEXT: [[TMP5:%.*]] = getelementptr inbounds i64, ptr [[B]], i64 [[TMP3]]
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr inbounds ptr, ptr [[A:%.*]], i64 [[OFFSET_IDX]]
; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds ptr, ptr [[A]], i64 [[TMP3]]
; CHECK-NEXT: store ptr [[TMP4]], ptr [[TMP6]], align 8
; CHECK-NEXT: store ptr [[TMP5]], ptr [[TMP7]], align 8
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
; CHECK-NEXT: [[TMP8:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP8]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[TMP2]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[IND_END]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[I:%.*]] = phi i64 [ [[I_NEXT:%.*]], [[FOR_BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[VAR0:%.*]] = getelementptr inbounds i64, ptr [[B]], i64 [[I]]
; CHECK-NEXT: [[VAR3:%.*]] = getelementptr inbounds ptr, ptr [[A]], i64 [[I]]
; CHECK-NEXT: store ptr [[VAR0]], ptr [[VAR3]], align 8
; CHECK-NEXT: [[I_NEXT]] = add nuw nsw i64 [[I]], 2
; CHECK-NEXT: [[COND:%.*]] = icmp slt i64 [[I_NEXT]], [[N]]
; CHECK-NEXT: br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END]], !llvm.loop [[LOOP7:![0-9]+]]
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
br label %for.body
for.body:
%i = phi i64 [ %i.next, %for.body ], [ 0, %entry ]
%var0 = getelementptr inbounds i64, ptr %b, i64 %i
%var3 = getelementptr inbounds ptr, ptr %a, i64 %i
store ptr %var0, ptr %var3, align 8
%i.next = add nuw nsw i64 %i, 2
%cond = icmp slt i64 %i.next, %n
br i1 %cond, label %for.body, label %for.end
for.end:
ret void
}
;
define void @no_gep_or_bitcast(ptr noalias %a, i64 %n) {
; CHECK-LABEL: @no_gep_or_bitcast(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SMAX:%.*]] = call i64 @llvm.smax.i64(i64 [[N:%.*]], i64 1)
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp slt i64 [[N]], 2
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_VEC:%.*]] = and i64 [[SMAX]], 9223372036854775806
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP0:%.*]] = getelementptr inbounds ptr, ptr [[A:%.*]], i64 [[INDEX]]
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <2 x ptr>, ptr [[TMP0]], align 8
; CHECK-NEXT: [[TMP1:%.*]] = extractelement <2 x ptr> [[WIDE_LOAD]], i64 0
; CHECK-NEXT: [[TMP2:%.*]] = extractelement <2 x ptr> [[WIDE_LOAD]], i64 1
; CHECK-NEXT: store i32 0, ptr [[TMP1]], align 8
; CHECK-NEXT: store i32 0, ptr [[TMP2]], align 8
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
; CHECK-NEXT: [[TMP3:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP3]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP8:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[SMAX]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[I:%.*]] = phi i64 [ [[I_NEXT:%.*]], [[FOR_BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[VAR0:%.*]] = getelementptr inbounds nuw ptr, ptr [[A]], i64 [[I]]
; CHECK-NEXT: [[VAR1:%.*]] = load ptr, ptr [[VAR0]], align 8
; CHECK-NEXT: store i32 0, ptr [[VAR1]], align 8
; CHECK-NEXT: [[I_NEXT]] = add nuw nsw i64 [[I]], 1
; CHECK-NEXT: [[COND:%.*]] = icmp slt i64 [[I_NEXT]], [[N]]
; CHECK-NEXT: br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END]], !llvm.loop [[LOOP9:![0-9]+]]
; CHECK: for.end:
; CHECK-NEXT: ret void
;
entry:
br label %for.body
for.body:
%i = phi i64 [ %i.next, %for.body ], [ 0, %entry ]
%var0 = getelementptr inbounds ptr, ptr %a, i64 %i
%var1 = load ptr, ptr %var0, align 8
store i32 0, ptr %var1, align 8
%i.next = add nuw nsw i64 %i, 1
%cond = icmp slt i64 %i.next, %n
br i1 %cond, label %for.body, label %for.end
for.end:
ret void
}
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