90ba33099c
This patch canonicalizes getelementptr instructions with constant indices to use the `i8` source element type. This makes it easier for optimizations to recognize that two GEPs are identical, because they don't need to see past many different ways to express the same offset. This is a first step towards https://discourse.llvm.org/t/rfc-replacing-getelementptr-with-ptradd/68699. This is limited to constant GEPs only for now, as they have a clear canonical form, while we're not yet sure how exactly to deal with variable indices. The test llvm/test/Transforms/PhaseOrdering/switch_with_geps.ll gives two representative examples of the kind of optimization improvement we expect from this change. In the first test SimplifyCFG can now realize that all switch branches are actually the same. In the second test it can convert it into simple arithmetic. These are representative of common optimization failures we see in Rust. Fixes https://github.com/llvm/llvm-project/issues/69841.
99 lines
5.7 KiB
LLVM
99 lines
5.7 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 < %s -passes=loop-vectorize,dce,instcombine -S | FileCheck -check-prefix=GFX9 %s
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; RUN: opt -mtriple=amdgcn-amd-amdhsa -mcpu=fiji < %s -passes=loop-vectorize,dce,instcombine -S | FileCheck -check-prefix=VI %s
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; RUN: opt -mtriple=amdgcn-amd-amdhsa -mcpu=hawaii < %s -passes=loop-vectorize,dce,instcombine -S | FileCheck -check-prefix=CI %s
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define half @vectorize_v2f16_loop(ptr addrspace(1) noalias %s) {
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; GFX9-LABEL: @vectorize_v2f16_loop(
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; GFX9-NEXT: entry:
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; GFX9-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
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; GFX9: vector.ph:
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; GFX9-NEXT: br label [[VECTOR_BODY:%.*]]
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; GFX9: vector.body:
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; GFX9-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
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; GFX9-NEXT: [[VEC_PHI:%.*]] = phi <2 x half> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP2:%.*]], [[VECTOR_BODY]] ]
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; GFX9-NEXT: [[VEC_PHI1:%.*]] = phi <2 x half> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP3:%.*]], [[VECTOR_BODY]] ]
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; GFX9-NEXT: [[TMP0:%.*]] = getelementptr inbounds half, ptr addrspace(1) [[S:%.*]], i64 [[INDEX]]
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; GFX9-NEXT: [[TMP1:%.*]] = getelementptr inbounds i8, ptr addrspace(1) [[TMP0]], i64 4
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; GFX9-NEXT: [[WIDE_LOAD:%.*]] = load <2 x half>, ptr addrspace(1) [[TMP0]], align 2
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; GFX9-NEXT: [[WIDE_LOAD2:%.*]] = load <2 x half>, ptr addrspace(1) [[TMP1]], align 2
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; GFX9-NEXT: [[TMP2]] = fadd fast <2 x half> [[VEC_PHI]], [[WIDE_LOAD]]
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; GFX9-NEXT: [[TMP3]] = fadd fast <2 x half> [[VEC_PHI1]], [[WIDE_LOAD2]]
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; GFX9-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
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; GFX9-NEXT: [[TMP4:%.*]] = icmp eq i64 [[INDEX_NEXT]], 256
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; GFX9-NEXT: br i1 [[TMP4]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
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; GFX9: middle.block:
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; GFX9-NEXT: [[BIN_RDX:%.*]] = fadd fast <2 x half> [[TMP3]], [[TMP2]]
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; GFX9-NEXT: [[TMP5:%.*]] = call fast half @llvm.vector.reduce.fadd.v2f16(half 0xH8000, <2 x half> [[BIN_RDX]])
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; GFX9-NEXT: br i1 true, label [[FOR_END:%.*]], label [[SCALAR_PH]]
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; GFX9: scalar.ph:
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; GFX9-NEXT: br label [[FOR_BODY:%.*]]
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; GFX9: for.body:
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; GFX9-NEXT: br i1 poison, label [[FOR_END]], label [[FOR_BODY]], !llvm.loop [[LOOP2:![0-9]+]]
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; GFX9: for.end:
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; GFX9-NEXT: [[ADD_LCSSA:%.*]] = phi half [ poison, [[FOR_BODY]] ], [ [[TMP5]], [[MIDDLE_BLOCK]] ]
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; GFX9-NEXT: ret half [[ADD_LCSSA]]
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;
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; VI-LABEL: @vectorize_v2f16_loop(
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; VI-NEXT: entry:
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; VI-NEXT: br i1 false, label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
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; VI: vector.ph:
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; VI-NEXT: br label [[VECTOR_BODY:%.*]]
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; VI: vector.body:
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; VI-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
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; VI-NEXT: [[VEC_PHI:%.*]] = phi <2 x half> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP2:%.*]], [[VECTOR_BODY]] ]
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; VI-NEXT: [[VEC_PHI1:%.*]] = phi <2 x half> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP3:%.*]], [[VECTOR_BODY]] ]
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; VI-NEXT: [[TMP0:%.*]] = getelementptr inbounds half, ptr addrspace(1) [[S:%.*]], i64 [[INDEX]]
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; VI-NEXT: [[TMP1:%.*]] = getelementptr inbounds i8, ptr addrspace(1) [[TMP0]], i64 4
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; VI-NEXT: [[WIDE_LOAD:%.*]] = load <2 x half>, ptr addrspace(1) [[TMP0]], align 2
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; VI-NEXT: [[WIDE_LOAD2:%.*]] = load <2 x half>, ptr addrspace(1) [[TMP1]], align 2
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; VI-NEXT: [[TMP2]] = fadd fast <2 x half> [[VEC_PHI]], [[WIDE_LOAD]]
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; VI-NEXT: [[TMP3]] = fadd fast <2 x half> [[VEC_PHI1]], [[WIDE_LOAD2]]
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; VI-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
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; VI-NEXT: [[TMP4:%.*]] = icmp eq i64 [[INDEX_NEXT]], 256
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; VI-NEXT: br i1 [[TMP4]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
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; VI: middle.block:
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; VI-NEXT: [[BIN_RDX:%.*]] = fadd fast <2 x half> [[TMP3]], [[TMP2]]
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; VI-NEXT: [[TMP5:%.*]] = call fast half @llvm.vector.reduce.fadd.v2f16(half 0xH8000, <2 x half> [[BIN_RDX]])
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; VI-NEXT: br i1 true, label [[FOR_END:%.*]], label [[SCALAR_PH]]
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; VI: scalar.ph:
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; VI-NEXT: br label [[FOR_BODY:%.*]]
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; VI: for.body:
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; VI-NEXT: br i1 poison, label [[FOR_END]], label [[FOR_BODY]], !llvm.loop [[LOOP2:![0-9]+]]
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; VI: for.end:
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; VI-NEXT: [[ADD_LCSSA:%.*]] = phi half [ poison, [[FOR_BODY]] ], [ [[TMP5]], [[MIDDLE_BLOCK]] ]
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; VI-NEXT: ret half [[ADD_LCSSA]]
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;
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; CI-LABEL: @vectorize_v2f16_loop(
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; CI-NEXT: entry:
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; CI-NEXT: br label [[FOR_BODY:%.*]]
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; CI: for.body:
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; CI-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[INDVARS_IV_NEXT:%.*]], [[FOR_BODY]] ]
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; CI-NEXT: [[Q_04:%.*]] = phi half [ 0xH0000, [[ENTRY]] ], [ [[ADD:%.*]], [[FOR_BODY]] ]
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; CI-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds half, ptr addrspace(1) [[S:%.*]], i64 [[INDVARS_IV]]
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; CI-NEXT: [[TMP0:%.*]] = load half, ptr addrspace(1) [[ARRAYIDX]], align 2
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; CI-NEXT: [[ADD]] = fadd fast half [[Q_04]], [[TMP0]]
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; CI-NEXT: [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 1
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; CI-NEXT: [[EXITCOND:%.*]] = icmp eq i64 [[INDVARS_IV_NEXT]], 256
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; CI-NEXT: br i1 [[EXITCOND]], label [[FOR_END:%.*]], label [[FOR_BODY]]
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; CI: for.end:
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; CI-NEXT: ret half [[ADD]]
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;
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entry:
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br label %for.body
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for.body:
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%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
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%q.04 = phi half [ 0.0, %entry ], [ %add, %for.body ]
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%arrayidx = getelementptr inbounds half, ptr addrspace(1) %s, i64 %indvars.iv
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%0 = load half, ptr addrspace(1) %arrayidx, align 2
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%add = fadd fast half %q.04, %0
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%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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%exitcond = icmp eq i64 %indvars.iv.next, 256
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br i1 %exitcond, label %for.end, label %for.body
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for.end:
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%add.lcssa = phi half [ %add, %for.body ]
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ret half %add.lcssa
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}
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