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.
145 lines
6.1 KiB
LLVM
145 lines
6.1 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -passes=instcombine %s -S | FileCheck %s
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@block = global [64 x [8192 x i8]] zeroinitializer, align 1
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define <2 x ptr> @vectorindex1() {
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; CHECK-LABEL: @vectorindex1(
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; CHECK-NEXT: ret <2 x ptr> getelementptr inbounds ([64 x [8192 x i8]], ptr @block, <2 x i64> zeroinitializer, <2 x i64> <i64 1, i64 2>, <2 x i64> zeroinitializer)
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;
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%1 = getelementptr inbounds [64 x [8192 x i8]], ptr @block, i64 0, <2 x i64> <i64 0, i64 1>, i64 8192
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ret <2 x ptr> %1
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}
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define <2 x ptr> @vectorindex2() {
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; CHECK-LABEL: @vectorindex2(
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; CHECK-NEXT: ret <2 x ptr> getelementptr inbounds ([64 x [8192 x i8]], ptr @block, <2 x i64> zeroinitializer, <2 x i64> <i64 1, i64 2>, <2 x i64> <i64 8191, i64 1>)
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;
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%1 = getelementptr inbounds [64 x [8192 x i8]], ptr @block, i64 0, i64 1, <2 x i64> <i64 8191, i64 8193>
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ret <2 x ptr> %1
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}
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define <2 x ptr> @vectorindex3() {
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; CHECK-LABEL: @vectorindex3(
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; CHECK-NEXT: ret <2 x ptr> getelementptr inbounds ([64 x [8192 x i8]], ptr @block, <2 x i64> zeroinitializer, <2 x i64> <i64 0, i64 2>, <2 x i64> <i64 8191, i64 1>)
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;
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%1 = getelementptr inbounds [64 x [8192 x i8]], ptr @block, i64 0, <2 x i64> <i64 0, i64 1>, <2 x i64> <i64 8191, i64 8193>
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ret <2 x ptr> %1
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}
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; Negative test - datalayout's alloc size for the 2 types must match.
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define ptr @bitcast_vec_to_array_gep(ptr %x, i64 %y, i64 %z) {
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; CHECK-LABEL: @bitcast_vec_to_array_gep(
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr [7 x i32], ptr [[X:%.*]], i64 [[Y:%.*]], i64 [[Z:%.*]]
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; CHECK-NEXT: ret ptr [[GEP]]
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;
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%gep = getelementptr [7 x i32], ptr %x, i64 %y, i64 %z
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ret ptr %gep
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}
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; Negative test - datalayout's alloc size for the 2 types must match.
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define ptr @bitcast_array_to_vec_gep(ptr %x, i64 %y, i64 %z) {
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; CHECK-LABEL: @bitcast_array_to_vec_gep(
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds <3 x i32>, ptr [[X:%.*]], i64 [[Y:%.*]], i64 [[Z:%.*]]
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; CHECK-NEXT: ret ptr [[GEP]]
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;
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%gep = getelementptr inbounds <3 x i32>, ptr %x, i64 %y, i64 %z
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ret ptr %gep
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}
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; Sizes and types match - safe to remove bitcast.
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define ptr @bitcast_vec_to_array_gep_matching_alloc_size(ptr %x, i64 %y, i64 %z) {
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; CHECK-LABEL: @bitcast_vec_to_array_gep_matching_alloc_size(
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr [4 x i32], ptr [[X:%.*]], i64 [[Y:%.*]], i64 [[Z:%.*]]
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; CHECK-NEXT: ret ptr [[GEP]]
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;
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%gep = getelementptr [4 x i32], ptr %x, i64 %y, i64 %z
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ret ptr %gep
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}
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; Sizes and types match - safe to remove bitcast.
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define ptr @bitcast_array_to_vec_gep_matching_alloc_size(ptr %x, i64 %y, i64 %z) {
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; CHECK-LABEL: @bitcast_array_to_vec_gep_matching_alloc_size(
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds <4 x i32>, ptr [[X:%.*]], i64 [[Y:%.*]], i64 [[Z:%.*]]
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; CHECK-NEXT: ret ptr [[GEP]]
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;
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%gep = getelementptr inbounds <4 x i32>, ptr %x, i64 %y, i64 %z
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ret ptr %gep
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}
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; Negative test - datalayout's alloc size for the 2 types must match.
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define ptr addrspace(3) @bitcast_vec_to_array_addrspace(ptr %x, i64 %y, i64 %z) {
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; CHECK-LABEL: @bitcast_vec_to_array_addrspace(
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; CHECK-NEXT: [[ASC:%.*]] = addrspacecast ptr [[X:%.*]] to ptr addrspace(3)
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr [7 x i32], ptr addrspace(3) [[ASC]], i64 [[Y:%.*]], i64 [[Z:%.*]]
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; CHECK-NEXT: ret ptr addrspace(3) [[GEP]]
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;
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%asc = addrspacecast ptr %x to ptr addrspace(3)
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%gep = getelementptr [7 x i32], ptr addrspace(3) %asc, i64 %y, i64 %z
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ret ptr addrspace(3) %gep
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}
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; Negative test - datalayout's alloc size for the 2 types must match.
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define ptr addrspace(3) @inbounds_bitcast_vec_to_array_addrspace(ptr %x, i64 %y, i64 %z) {
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; CHECK-LABEL: @inbounds_bitcast_vec_to_array_addrspace(
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; CHECK-NEXT: [[ASC:%.*]] = addrspacecast ptr [[X:%.*]] to ptr addrspace(3)
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds [7 x i32], ptr addrspace(3) [[ASC]], i64 [[Y:%.*]], i64 [[Z:%.*]]
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; CHECK-NEXT: ret ptr addrspace(3) [[GEP]]
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;
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%asc = addrspacecast ptr %x to ptr addrspace(3)
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%gep = getelementptr inbounds [7 x i32], ptr addrspace(3) %asc, i64 %y, i64 %z
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ret ptr addrspace(3) %gep
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}
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; Sizes and types match - safe to remove bitcast.
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define ptr addrspace(3) @bitcast_vec_to_array_addrspace_matching_alloc_size(ptr %x, i64 %y, i64 %z) {
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; CHECK-LABEL: @bitcast_vec_to_array_addrspace_matching_alloc_size(
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; CHECK-NEXT: [[ASC:%.*]] = addrspacecast ptr [[X:%.*]] to ptr addrspace(3)
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr [4 x i32], ptr addrspace(3) [[ASC]], i64 [[Y:%.*]], i64 [[Z:%.*]]
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; CHECK-NEXT: ret ptr addrspace(3) [[GEP]]
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;
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%asc = addrspacecast ptr %x to ptr addrspace(3)
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%gep = getelementptr [4 x i32], ptr addrspace(3) %asc, i64 %y, i64 %z
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ret ptr addrspace(3) %gep
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}
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; Sizes and types match - safe to remove bitcast.
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define ptr addrspace(3) @inbounds_bitcast_vec_to_array_addrspace_matching_alloc_size(ptr %x, i64 %y, i64 %z) {
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; CHECK-LABEL: @inbounds_bitcast_vec_to_array_addrspace_matching_alloc_size(
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; CHECK-NEXT: [[ASC:%.*]] = addrspacecast ptr [[X:%.*]] to ptr addrspace(3)
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr inbounds [4 x i32], ptr addrspace(3) [[ASC]], i64 [[Y:%.*]], i64 [[Z:%.*]]
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; CHECK-NEXT: ret ptr addrspace(3) [[GEP]]
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;
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%asc = addrspacecast ptr %x to ptr addrspace(3)
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%gep = getelementptr inbounds [4 x i32], ptr addrspace(3) %asc, i64 %y, i64 %z
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ret ptr addrspace(3) %gep
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}
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; Negative test - avoid doing bitcast on ptr, because '16' should be scaled by 'vscale'.
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define ptr @test_accumulate_constant_offset_vscale_nonzero(<vscale x 16 x i1> %pg, ptr %base) {
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; CHECK-LABEL: @test_accumulate_constant_offset_vscale_nonzero(
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr <vscale x 16 x i8>, ptr [[BASE:%.*]], i64 1, i64 4
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; CHECK-NEXT: ret ptr [[GEP]]
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;
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%gep = getelementptr <vscale x 16 x i8>, ptr %base, i64 1, i64 4
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ret ptr %gep
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}
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define ptr @test_accumulate_constant_offset_vscale_zero(<vscale x 16 x i1> %pg, ptr %base) {
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; CHECK-LABEL: @test_accumulate_constant_offset_vscale_zero(
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; CHECK-NEXT: [[GEP:%.*]] = getelementptr i8, ptr [[BASE:%.*]], i64 4
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; CHECK-NEXT: ret ptr [[GEP]]
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;
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%gep = getelementptr <vscale x 16 x i8>, ptr %base, i64 0, i64 4
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ret ptr %gep
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}
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