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llvm-project/llvm/test/Transforms/InstCombine/memrchr-5.ll
Nikita Popov 90ba33099c
[InstCombine] Canonicalize constant GEPs to i8 source element type (#68882) 
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.
2024-01-24 15:25:29 +01:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; Verify that calls to memrchr with arrays of elements larger than char
; are folded correctly.
; RUN: opt < %s -passes=instcombine -S -data-layout="E" | FileCheck %s --check-prefixes=BE
; RUN: opt < %s -passes=instcombine -S -data-layout="e" | FileCheck %s --check-prefixes=LE
declare ptr @memrchr(ptr, i32, i64)
; BE representation: { 'a', 'b', 'c', 'd', 'e', ..., 'p', 'a', 'b', 'c', 'd' }
; LE representation: { 'd', 'c', 'b', 'a', 'h', ..., 'm', 'd', 'c', 'b', 'a' }
@a = constant [5 x i32] [i32 1633837924, i32 1701209960, i32 1768581996, i32 1835954032, i32 1633837924]
; Fold memrchr(a, C, 16) for C in ['a', 'd'] U ['o', 'q'].
define void @fold_memrchr_a_16(ptr %pcmp) {
; BE-LABEL: @fold_memrchr_a_16(
; BE-NEXT: store i64 0, ptr [[PCMP:%.*]], align 4
; BE-NEXT: [[PSTOR1:%.*]] = getelementptr i8, ptr [[PCMP]], i64 8
; BE-NEXT: store i64 1, ptr [[PSTOR1]], align 4
; BE-NEXT: [[PSTOR2:%.*]] = getelementptr i8, ptr [[PCMP]], i64 16
; BE-NEXT: store i64 2, ptr [[PSTOR2]], align 4
; BE-NEXT: [[PSTOR3:%.*]] = getelementptr i8, ptr [[PCMP]], i64 24
; BE-NEXT: store i64 3, ptr [[PSTOR3]], align 4
; BE-NEXT: [[PSTOR4:%.*]] = getelementptr i8, ptr [[PCMP]], i64 32
; BE-NEXT: store i64 13, ptr [[PSTOR4]], align 4
; BE-NEXT: [[PSTOR6:%.*]] = getelementptr i8, ptr [[PCMP]], i64 48
; BE-NEXT: store i64 14, ptr [[PSTOR6]], align 4
; BE-NEXT: [[PSTOR7:%.*]] = getelementptr i8, ptr [[PCMP]], i64 56
; BE-NEXT: store i64 15, ptr [[PSTOR7]], align 4
; BE-NEXT: [[PSTOR8:%.*]] = getelementptr i8, ptr [[PCMP]], i64 64
; BE-NEXT: store i64 0, ptr [[PSTOR8]], align 4
; BE-NEXT: ret void
;
; LE-LABEL: @fold_memrchr_a_16(
; LE-NEXT: store i64 3, ptr [[PCMP:%.*]], align 4
; LE-NEXT: [[PSTOR1:%.*]] = getelementptr i8, ptr [[PCMP]], i64 8
; LE-NEXT: store i64 2, ptr [[PSTOR1]], align 4
; LE-NEXT: [[PSTOR2:%.*]] = getelementptr i8, ptr [[PCMP]], i64 16
; LE-NEXT: store i64 1, ptr [[PSTOR2]], align 4
; LE-NEXT: [[PSTOR3:%.*]] = getelementptr i8, ptr [[PCMP]], i64 24
; LE-NEXT: store i64 0, ptr [[PSTOR3]], align 4
; LE-NEXT: [[PSTOR4:%.*]] = getelementptr i8, ptr [[PCMP]], i64 32
; LE-NEXT: store i64 14, ptr [[PSTOR4]], align 4
; LE-NEXT: [[PSTOR6:%.*]] = getelementptr i8, ptr [[PCMP]], i64 48
; LE-NEXT: store i64 13, ptr [[PSTOR6]], align 4
; LE-NEXT: [[PSTOR7:%.*]] = getelementptr i8, ptr [[PCMP]], i64 56
; LE-NEXT: store i64 12, ptr [[PSTOR7]], align 4
; LE-NEXT: [[PSTOR8:%.*]] = getelementptr i8, ptr [[PCMP]], i64 64
; LE-NEXT: store i64 0, ptr [[PSTOR8]], align 4
; LE-NEXT: ret void
;
%ip0 = ptrtoint ptr @a to i64
; Fold memrchr(a, 'a', 16) - a to 0 (3 in LE).
%pa = call ptr @memrchr(ptr @a, i32 97, i64 16)
%ipa = ptrtoint ptr %pa to i64
%offa = sub i64 %ipa, %ip0
store i64 %offa, ptr %pcmp
; Fold memrchr(a, 'b', 16) - a to 1 (2 in LE)
%pb = call ptr @memrchr(ptr @a, i32 98, i64 16)
%ipb = ptrtoint ptr %pb to i64
%offb = sub i64 %ipb, %ip0
%pstor1 = getelementptr i64, ptr %pcmp, i64 1
store i64 %offb, ptr %pstor1
; Fold memrchr(a, 'c', 16) - a to 2 (1 in LE)
%pc = call ptr @memrchr(ptr @a, i32 99, i64 16)
%ipc = ptrtoint ptr %pc to i64
%offc = sub i64 %ipc, %ip0
%pstor2 = getelementptr i64, ptr %pcmp, i64 2
store i64 %offc, ptr %pstor2
; Fold memrchr(a, 'd', 16) - a to 3 (0 in LE)
%pd = call ptr @memrchr(ptr @a, i32 100, i64 16)
%ipd = ptrtoint ptr %pd to i64
%offd = sub i64 %ipd, %ip0
%pstor3 = getelementptr i64, ptr %pcmp, i64 3
store i64 %offd, ptr %pstor3
; Fold memrchr(a, 'n', 16) - a to 13 (14 in LE)
%pn = call ptr @memrchr(ptr @a, i32 110, i64 16)
%ipn = ptrtoint ptr %pn to i64
%offn = sub i64 %ipn, %ip0
%pstor4 = getelementptr i64, ptr %pcmp, i64 4
store i64 %offn, ptr %pstor4
; Fold memrchr(a, 'o', 16) - a to 14 (13 in LE)
%po = call ptr @memrchr(ptr @a, i32 111, i64 16)
%ipo = ptrtoint ptr %po to i64
%offo = sub i64 %ipo, %ip0
%pstor6 = getelementptr i64, ptr %pcmp, i64 6
store i64 %offo, ptr %pstor6
; Fold memrchr(a, 'p', 16) - a to 15 (12 in LE)
%pp = call ptr @memrchr(ptr @a, i32 112, i64 16)
%ipp = ptrtoint ptr %pp to i64
%offp = sub i64 %ipp, %ip0
%pstor7 = getelementptr i64, ptr %pcmp, i64 7
store i64 %offp, ptr %pstor7
; Fold memrchr(a, 'q', 16) to null in both BE and LE.
%pq = call ptr @memrchr(ptr @a, i32 113, i64 16)
%ipq = ptrtoint ptr %pq to i64
%pstor8 = getelementptr i64, ptr %pcmp, i64 8
store i64 %ipq, ptr %pstor8
ret void
}
; Fold memrchr(a + 1, C, 12) for C in ['e', 'h'] U ['a', 'd'].
define void @fold_memrchr_a_p1_16(ptr %pcmp) {
; BE-LABEL: @fold_memrchr_a_p1_16(
; BE-NEXT: store i64 0, ptr [[PCMP:%.*]], align 4
; BE-NEXT: [[PSTOR1:%.*]] = getelementptr i8, ptr [[PCMP]], i64 8
; BE-NEXT: store i64 1, ptr [[PSTOR1]], align 4
; BE-NEXT: [[PSTOR2:%.*]] = getelementptr i8, ptr [[PCMP]], i64 16
; BE-NEXT: store i64 2, ptr [[PSTOR2]], align 4
; BE-NEXT: [[PSTOR3:%.*]] = getelementptr i8, ptr [[PCMP]], i64 24
; BE-NEXT: store i64 3, ptr [[PSTOR3]], align 4
; BE-NEXT: [[PSTOR4:%.*]] = getelementptr i8, ptr [[PCMP]], i64 32
; BE-NEXT: store i64 0, ptr [[PSTOR4]], align 4
; BE-NEXT: [[PSTOR5:%.*]] = getelementptr i8, ptr [[PCMP]], i64 40
; BE-NEXT: store i64 0, ptr [[PSTOR5]], align 4
; BE-NEXT: ret void
;
; LE-LABEL: @fold_memrchr_a_p1_16(
; LE-NEXT: store i64 3, ptr [[PCMP:%.*]], align 4
; LE-NEXT: [[PSTOR1:%.*]] = getelementptr i8, ptr [[PCMP]], i64 8
; LE-NEXT: store i64 2, ptr [[PSTOR1]], align 4
; LE-NEXT: [[PSTOR2:%.*]] = getelementptr i8, ptr [[PCMP]], i64 16
; LE-NEXT: store i64 1, ptr [[PSTOR2]], align 4
; LE-NEXT: [[PSTOR3:%.*]] = getelementptr i8, ptr [[PCMP]], i64 24
; LE-NEXT: store i64 0, ptr [[PSTOR3]], align 4
; LE-NEXT: [[PSTOR4:%.*]] = getelementptr i8, ptr [[PCMP]], i64 32
; LE-NEXT: store i64 0, ptr [[PSTOR4]], align 4
; LE-NEXT: [[PSTOR5:%.*]] = getelementptr i8, ptr [[PCMP]], i64 40
; LE-NEXT: store i64 0, ptr [[PSTOR5]], align 4
; LE-NEXT: ret void
;
%p0 = getelementptr [5 x i32], ptr @a, i64 0, i64 1
%ip0 = ptrtoint ptr %p0 to i64
; Fold memrchr(a + 1, 'e', 12) - a to 0 (3 in LE).
%pe = call ptr @memrchr(ptr %p0, i32 101, i64 12)
%ipe = ptrtoint ptr %pe to i64
%offe = sub i64 %ipe, %ip0
store i64 %offe, ptr %pcmp
; Fold memrchr(a + 1, 'f', 12) - a to 1 (2 in LE).
%pf = call ptr @memrchr(ptr %p0, i32 102, i64 12)
%ipf = ptrtoint ptr %pf to i64
%offf = sub i64 %ipf, %ip0
%pstor1 = getelementptr i64, ptr %pcmp, i64 1
store i64 %offf, ptr %pstor1
; Fold memrchr(a + 1, 'g', 12) - a to 2 (1 in LE).
%pg = call ptr @memrchr(ptr %p0, i32 103, i64 12)
%ipg = ptrtoint ptr %pg to i64
%offg = sub i64 %ipg, %ip0
%pstor2 = getelementptr i64, ptr %pcmp, i64 2
store i64 %offg, ptr %pstor2
; Fold memrchr(a + 1, 'h', 12) - a to 3 (0 in LE).
%ph = call ptr @memrchr(ptr %p0, i32 104, i64 12)
%iph = ptrtoint ptr %ph to i64
%offh = sub i64 %iph, %ip0
%pstor3 = getelementptr i64, ptr %pcmp, i64 3
store i64 %offh, ptr %pstor3
; Fold memrchr(a + 1, 'a', 12) to null in both BE and LE.
%pa = call ptr @memrchr(ptr %p0, i32 97, i64 12)
%ipa = ptrtoint ptr %pa to i64
%pstor4 = getelementptr i64, ptr %pcmp, i64 4
store i64 %ipa, ptr %pstor4
; Fold memrchr(a + 1, 'd', 12) to null in both BE and LE.
%pd = call ptr @memrchr(ptr %p0, i32 100, i64 12)
%ipd = ptrtoint ptr %pd to i64
%pstor5 = getelementptr i64, ptr %pcmp, i64 5
store i64 %ipd, ptr %pstor5
ret void
}
; Fold memrchr(a, C, 20) for C in ['a', 'e'].
define void @fold_memrchr_a_20(ptr %pcmp) {
; BE-LABEL: @fold_memrchr_a_20(
; BE-NEXT: store i64 16, ptr [[PCMP:%.*]], align 4
; BE-NEXT: [[PSTOR1:%.*]] = getelementptr i8, ptr [[PCMP]], i64 8
; BE-NEXT: store i64 17, ptr [[PSTOR1]], align 4
; BE-NEXT: [[PSTOR2:%.*]] = getelementptr i8, ptr [[PCMP]], i64 16
; BE-NEXT: store i64 18, ptr [[PSTOR2]], align 4
; BE-NEXT: [[PSTOR3:%.*]] = getelementptr i8, ptr [[PCMP]], i64 24
; BE-NEXT: store i64 19, ptr [[PSTOR3]], align 4
; BE-NEXT: [[PSTOR4:%.*]] = getelementptr i8, ptr [[PCMP]], i64 32
; BE-NEXT: store i64 4, ptr [[PSTOR4]], align 4
; BE-NEXT: ret void
;
; LE-LABEL: @fold_memrchr_a_20(
; LE-NEXT: store i64 19, ptr [[PCMP:%.*]], align 4
; LE-NEXT: [[PSTOR1:%.*]] = getelementptr i8, ptr [[PCMP]], i64 8
; LE-NEXT: store i64 18, ptr [[PSTOR1]], align 4
; LE-NEXT: [[PSTOR2:%.*]] = getelementptr i8, ptr [[PCMP]], i64 16
; LE-NEXT: store i64 17, ptr [[PSTOR2]], align 4
; LE-NEXT: [[PSTOR3:%.*]] = getelementptr i8, ptr [[PCMP]], i64 24
; LE-NEXT: store i64 16, ptr [[PSTOR3]], align 4
; LE-NEXT: [[PSTOR4:%.*]] = getelementptr i8, ptr [[PCMP]], i64 32
; LE-NEXT: store i64 7, ptr [[PSTOR4]], align 4
; LE-NEXT: ret void
;
%ip0 = ptrtoint ptr @a to i64
; Fold memrchr(a, 'a', 20) - a to 16 (19 in LE).
%pa = call ptr @memrchr(ptr @a, i32 97, i64 20)
%ipa = ptrtoint ptr %pa to i64
%offa = sub i64 %ipa, %ip0
store i64 %offa, ptr %pcmp
; Fold memrchr(a, 'b', 16) - a to 17 (18 in LE)
%pb = call ptr @memrchr(ptr @a, i32 98, i64 20)
%ipb = ptrtoint ptr %pb to i64
%offb = sub i64 %ipb, %ip0
%pstor1 = getelementptr i64, ptr %pcmp, i64 1
store i64 %offb, ptr %pstor1
; Fold memrchr(a, 'c', 16) - a to 18 (17 in LE)
%pc = call ptr @memrchr(ptr @a, i32 99, i64 20)
%ipc = ptrtoint ptr %pc to i64
%offc = sub i64 %ipc, %ip0
%pstor2 = getelementptr i64, ptr %pcmp, i64 2
store i64 %offc, ptr %pstor2
; Fold memrchr(a, 'd', 16) - a to 19 (16 in LE)
%pd = call ptr @memrchr(ptr @a, i32 100, i64 20)
%ipd = ptrtoint ptr %pd to i64
%offd = sub i64 %ipd, %ip0
%pstor3 = getelementptr i64, ptr %pcmp, i64 3
store i64 %offd, ptr %pstor3
; Fold memrchr(a, 'e', 16) - a to 4 (7 in LE)
%pe = call ptr @memrchr(ptr @a, i32 101, i64 20)
%ipe = ptrtoint ptr %pe to i64
%offe = sub i64 %ipe, %ip0
%pstor4 = getelementptr i64, ptr %pcmp, i64 4
store i64 %offe, ptr %pstor4
ret void
}
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