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clang-p2996/llvm/test/Transforms/InstCombine/str-int-3.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 atoi and related conversion functions with members
; of constant structs as arguments are folded to constants as expected.
; RUN: opt < %s -passes=instcombine -S | FileCheck %s
declare i32 @atoi(ptr)
declare i64 @atol(ptr)
declare i64 @atoll(ptr)
declare i64 @strtol(ptr, ptr, i32)
declare i64 @strtoll(ptr, ptr, i32)
%struct.A = type { [4 x i8], [5 x i8], [7 x i8] }
@a = constant [2 x %struct.A] [%struct.A { [4 x i8] c"1\00\00\00", [5 x i8] c"12\00\00\00", [7 x i8] c"56789\00\00" }, %struct.A { [4 x i8] c"123\00", [5 x i8] c"1234\00", [7 x i8] c"67890\00\00" }]
; Fold atoi(a[I].M) for constant I in [0, 1] and member M in [a, b]
; to a constant.
define void @fold_atoi_member(ptr %pi) {
; CHECK-LABEL: @fold_atoi_member(
; CHECK-NEXT: store i32 1, ptr [[PI:%.*]], align 4
; CHECK-NEXT: [[PIA0B:%.*]] = getelementptr i8, ptr [[PI]], i64 4
; CHECK-NEXT: store i32 12, ptr [[PIA0B]], align 4
; CHECK-NEXT: [[PIA1A:%.*]] = getelementptr i8, ptr [[PI]], i64 8
; CHECK-NEXT: store i32 123, ptr [[PIA1A]], align 4
; CHECK-NEXT: [[PIA1B:%.*]] = getelementptr i8, ptr [[PI]], i64 12
; CHECK-NEXT: store i32 1234, ptr [[PIA1B]], align 4
; CHECK-NEXT: ret void
;
; Fold atoi(a[0].a) to 1.
%ia0a = call i32 @atoi(ptr @a)
store i32 %ia0a, ptr %pi
; Fold atoi(a[0].b) to 12.
%pa0b = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 1, i64 0
%ia0b = call i32 @atoi(ptr %pa0b)
%pia0b = getelementptr i32, ptr %pi, i32 1
store i32 %ia0b, ptr %pia0b
; Fold atoi(a[1].a) to 123.
%pa1a = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 0, i64 0
%ia1a = call i32 @atoi(ptr %pa1a)
%pia1a = getelementptr i32, ptr %pi, i32 2
store i32 %ia1a, ptr %pia1a
; Fold atoi(a[1].b) to 1234.
%pa1b = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 1, i64 0
%ia1b = call i32 @atoi(ptr %pa1b)
%pia1b = getelementptr i32, ptr %pi, i32 3
store i32 %ia1b, ptr %pia1b
ret void
}
; TODO: Fold atoi with an excessive offset. It's undefined so folding it
; to zero is valid and might prevent crashes or returning a bogus value,
; even though it prevents detecting the bug by sanitizers.
; This is not fully implemented because the out-of-bounds offset results
; in the empty string which atoi (via strtol) is required to interpret as
; a zero but for which it may set errno to EINVAL. To fold only
; the undefined calls the folder would have to differentiate between
; the empty string an out-of-bounds pointer.
define void @fold_atoi_offset_out_of_bounds(ptr %pi) {
; CHECK-LABEL: @fold_atoi_offset_out_of_bounds(
; CHECK-NEXT: [[IA_0_0_32:%.*]] = call i32 @atoi(ptr nocapture nonnull getelementptr inbounds ([2 x %struct.A], ptr @a, i64 1, i64 0, i32 0, i64 0))
; CHECK-NEXT: store i32 [[IA_0_0_32]], ptr [[PI:%.*]], align 4
; CHECK-NEXT: [[IA_0_0_33:%.*]] = call i32 @atoi(ptr nocapture getelementptr ([2 x %struct.A], ptr @a, i64 1, i64 0, i32 0, i64 1))
; CHECK-NEXT: store i32 [[IA_0_0_33]], ptr [[PI]], align 4
; CHECK-NEXT: ret void
;
; TODO: Check folding.
; Fold atoi((const char*)a + sizeof a) to zero.
%ia_0_0_32 = call i32 @atoi(ptr getelementptr inbounds ([2 x %struct.A], ptr @a, i64 1, i64 0, i32 0, i64 0))
store i32 %ia_0_0_32, ptr %pi
; Likewise, fold atoi((const char*)a + sizeof a + 1) to zero.
%pa_0_0_33 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 0, i64 33
%ia_0_0_33 = call i32 @atoi(ptr %pa_0_0_33)
store i32 %ia_0_0_33, ptr %pi
ret void
}
; Fold atol(a[I].M) for constant I in [0, 1] and member M in [a, b, c]
; to a constant.
define void @fold_atol_member(ptr %pi) {
; CHECK-LABEL: @fold_atol_member(
; CHECK-NEXT: store i64 1, ptr [[PI:%.*]], align 4
; CHECK-NEXT: [[PIA0B:%.*]] = getelementptr i8, ptr [[PI]], i64 8
; CHECK-NEXT: store i64 12, ptr [[PIA0B]], align 4
; CHECK-NEXT: [[PIA0C:%.*]] = getelementptr i8, ptr [[PI]], i64 16
; CHECK-NEXT: store i64 56789, ptr [[PIA0C]], align 4
; CHECK-NEXT: [[PIA1A:%.*]] = getelementptr i8, ptr [[PI]], i64 24
; CHECK-NEXT: store i64 123, ptr [[PIA1A]], align 4
; CHECK-NEXT: [[PIA1B:%.*]] = getelementptr i8, ptr [[PI]], i64 32
; CHECK-NEXT: store i64 1234, ptr [[PIA1B]], align 4
; CHECK-NEXT: [[PIA1C:%.*]] = getelementptr i8, ptr [[PI]], i64 40
; CHECK-NEXT: store i64 67890, ptr [[PIA1C]], align 4
; CHECK-NEXT: ret void
;
; Fold atol(a[0].a) to 1.
%ia0a = call i64 @atol(ptr @a)
store i64 %ia0a, ptr %pi
; Fold atol(a[0].b) to 12.
%pa0b = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 1, i64 0
%ia0b = call i64 @atol(ptr %pa0b)
%pia0b = getelementptr i64, ptr %pi, i32 1
store i64 %ia0b, ptr %pia0b
; Fold atol(a[0].c) to 56789.
%pa0c = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 2, i64 0
%ia0c = call i64 @atol(ptr %pa0c)
%pia0c = getelementptr i64, ptr %pi, i32 2
store i64 %ia0c, ptr %pia0c
; Fold atol(a[1].a) to 123.
%pa1a = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 0, i64 0
%ia1a = call i64 @atol(ptr %pa1a)
%pia1a = getelementptr i64, ptr %pi, i32 3
store i64 %ia1a, ptr %pia1a
; Fold atol(a[1].b) to 1234.
%pa1b = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 1, i64 0
%ia1b = call i64 @atol(ptr %pa1b)
%pia1b = getelementptr i64, ptr %pi, i32 4
store i64 %ia1b, ptr %pia1b
; Fold atol(a[1].c) to 67890.
%pa1c = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 2, i64 0
%ia1c = call i64 @atol(ptr %pa1c)
%pia1c = getelementptr i64, ptr %pi, i32 5
store i64 %ia1c, ptr %pia1c
ret void
}
; Fold atoll(a[I].M + C) for constant I in [0, 1], member M in [a, b, c],
; and C in a valid range to a constant.
define void @fold_atoll_member_pC(ptr %pi) {
; CHECK-LABEL: @fold_atoll_member_pC(
; CHECK-NEXT: store i64 1, ptr [[PI:%.*]], align 4
; CHECK-NEXT: [[PIA0BP1:%.*]] = getelementptr i8, ptr [[PI]], i64 8
; CHECK-NEXT: store i64 2, ptr [[PIA0BP1]], align 4
; CHECK-NEXT: [[PIA0CP3:%.*]] = getelementptr i8, ptr [[PI]], i64 16
; CHECK-NEXT: store i64 89, ptr [[PIA0CP3]], align 4
; CHECK-NEXT: [[PIA1AP2:%.*]] = getelementptr i8, ptr [[PI]], i64 24
; CHECK-NEXT: store i64 3, ptr [[PIA1AP2]], align 4
; CHECK-NEXT: [[PIA1BP3:%.*]] = getelementptr i8, ptr [[PI]], i64 32
; CHECK-NEXT: store i64 4, ptr [[PIA1BP3]], align 4
; CHECK-NEXT: [[PIA1CP4:%.*]] = getelementptr i8, ptr [[PI]], i64 40
; CHECK-NEXT: store i64 0, ptr [[PIA1CP4]], align 4
; CHECK-NEXT: ret void
;
; Fold atoll(a[0].a) to 1.
%ia0a = call i64 @atol(ptr @a)
store i64 %ia0a, ptr %pi
; Fold atoll(a[0].b + 1) to 2.
%pa0bp1 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 1, i64 1
%ia0bp1 = call i64 @atol(ptr %pa0bp1)
%pia0bp1 = getelementptr i64, ptr %pi, i32 1
store i64 %ia0bp1, ptr %pia0bp1
; Fold atoll(a[0].c + 3) to 89.
%pa0cp3 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 2, i64 3
%ia0cp3 = call i64 @atol(ptr %pa0cp3)
%pia0cp3 = getelementptr i64, ptr %pi, i32 2
store i64 %ia0cp3, ptr %pia0cp3
; Fold atoll(a[1].a + 2) to 3.
%pa1ap2 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 0, i64 2
%ia1ap2 = call i64 @atol(ptr %pa1ap2)
%pia1ap2 = getelementptr i64, ptr %pi, i32 3
store i64 %ia1ap2, ptr %pia1ap2
; Fold atoll(a[1].b + 3) to 4.
%pa1bp3 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 1, i64 3
%ia1bp3 = call i64 @atol(ptr %pa1bp3)
%pia1bp3 = getelementptr i64, ptr %pi, i32 4
store i64 %ia1bp3, ptr %pia1bp3
; Fold atoll(a[1].c + 4) to 0.
%pa1cp4 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 2, i64 4
%ia1cp4 = call i64 @atol(ptr %pa1cp4)
%pia1cp4 = getelementptr i64, ptr %pi, i32 5
store i64 %ia1cp4, ptr %pia1cp4
ret void
}
; Fold strtol(a[I].M + C, 0, 0) for constant I in [0, 1], member M in [a, b, c],
; and C in a valid range to a constant.
define void @fold_strtol_member_pC(ptr %pi) {
; CHECK-LABEL: @fold_strtol_member_pC(
; CHECK-NEXT: store i64 1, ptr [[PI:%.*]], align 4
; CHECK-NEXT: [[PIA0BP1:%.*]] = getelementptr i8, ptr [[PI]], i64 8
; CHECK-NEXT: store i64 2, ptr [[PIA0BP1]], align 4
; CHECK-NEXT: [[PIA0CP3:%.*]] = getelementptr i8, ptr [[PI]], i64 16
; CHECK-NEXT: store i64 89, ptr [[PIA0CP3]], align 4
; CHECK-NEXT: [[PIA1AP2:%.*]] = getelementptr i8, ptr [[PI]], i64 24
; CHECK-NEXT: store i64 3, ptr [[PIA1AP2]], align 4
; CHECK-NEXT: [[PIA1BP3:%.*]] = getelementptr i8, ptr [[PI]], i64 32
; CHECK-NEXT: store i64 4, ptr [[PIA1BP3]], align 4
; CHECK-NEXT: [[PIA1CP4:%.*]] = getelementptr i8, ptr [[PI]], i64 40
; CHECK-NEXT: store i64 0, ptr [[PIA1CP4]], align 4
; CHECK-NEXT: ret void
;
; Fold strtol(a[0].a, 0, 0) to 1.
%ia0a = call i64 @strtol(ptr @a, ptr null, i32 0)
store i64 %ia0a, ptr %pi
; Fold strtol(a[0].b + 1, 0, 0, ptr null, i32 0) to 2.
%pa0bp1 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 1, i64 1
%ia0bp1 = call i64 @strtol(ptr %pa0bp1, ptr null, i32 0)
%pia0bp1 = getelementptr i64, ptr %pi, i32 1
store i64 %ia0bp1, ptr %pia0bp1
; Fold strtol(a[0].c + 3, 0, 0, ptr null, i32 0) to 89.
%pa0cp3 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 2, i64 3
%ia0cp3 = call i64 @strtol(ptr %pa0cp3, ptr null, i32 0)
%pia0cp3 = getelementptr i64, ptr %pi, i32 2
store i64 %ia0cp3, ptr %pia0cp3
; Fold strtol(a[1].a + 2, 0, 0, ptr null, i32 0) to 3.
%pa1ap2 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 0, i64 2
%ia1ap2 = call i64 @strtol(ptr %pa1ap2, ptr null, i32 0)
%pia1ap2 = getelementptr i64, ptr %pi, i32 3
store i64 %ia1ap2, ptr %pia1ap2
; Fold strtol(a[1].b + 3, 0, 0, ptr null, i32 0) to 4.
%pa1bp3 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 1, i64 3
%ia1bp3 = call i64 @strtol(ptr %pa1bp3, ptr null, i32 0)
%pia1bp3 = getelementptr i64, ptr %pi, i32 4
store i64 %ia1bp3, ptr %pia1bp3
; Fold strtol(a[1].c + 4, 0, 0, ptr null, i32 0) to 0.
%pa1cp4 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 2, i64 4
%ia1cp4 = call i64 @strtol(ptr %pa1cp4, ptr null, i32 0)
%pia1cp4 = getelementptr i64, ptr %pi, i32 5
store i64 %ia1cp4, ptr %pia1cp4
ret void
}
; Fold strtoll(a[I].M + C, 0, 0) for constant I in [0, 1], member M
; in [a, b, c], and C in a valid range to a constant.
define void @fold_strtoll_member_pC(ptr %pi) {
; CHECK-LABEL: @fold_strtoll_member_pC(
; CHECK-NEXT: store i64 1, ptr [[PI:%.*]], align 4
; CHECK-NEXT: [[PIA0BP1:%.*]] = getelementptr i8, ptr [[PI]], i64 8
; CHECK-NEXT: store i64 2, ptr [[PIA0BP1]], align 4
; CHECK-NEXT: [[PIA0CP3:%.*]] = getelementptr i8, ptr [[PI]], i64 16
; CHECK-NEXT: store i64 89, ptr [[PIA0CP3]], align 4
; CHECK-NEXT: [[PIA1AP2:%.*]] = getelementptr i8, ptr [[PI]], i64 24
; CHECK-NEXT: store i64 3, ptr [[PIA1AP2]], align 4
; CHECK-NEXT: [[PIA1BP3:%.*]] = getelementptr i8, ptr [[PI]], i64 32
; CHECK-NEXT: store i64 4, ptr [[PIA1BP3]], align 4
; CHECK-NEXT: [[PIA1CP4:%.*]] = getelementptr i8, ptr [[PI]], i64 40
; CHECK-NEXT: store i64 0, ptr [[PIA1CP4]], align 4
; CHECK-NEXT: ret void
;
; Fold strtoll(a[0].a, 0, 0) to 1.
%ia0a = call i64 @strtoll(ptr @a, ptr null, i32 0)
store i64 %ia0a, ptr %pi
; Fold strtoll(a[0].b + 1, 0, 0, ptr null, i32 0) to 2.
%pa0bp1 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 1, i64 1
%ia0bp1 = call i64 @strtoll(ptr %pa0bp1, ptr null, i32 0)
%pia0bp1 = getelementptr i64, ptr %pi, i32 1
store i64 %ia0bp1, ptr %pia0bp1
; Fold strtoll(a[0].c + 3, 0, 0, ptr null, i32 0) to 89.
%pa0cp3 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 0, i32 2, i64 3
%ia0cp3 = call i64 @strtoll(ptr %pa0cp3, ptr null, i32 0)
%pia0cp3 = getelementptr i64, ptr %pi, i32 2
store i64 %ia0cp3, ptr %pia0cp3
; Fold strtoll(a[1].a + 2, 0, 0, ptr null, i32 0) to 3.
%pa1ap2 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 0, i64 2
%ia1ap2 = call i64 @strtoll(ptr %pa1ap2, ptr null, i32 0)
%pia1ap2 = getelementptr i64, ptr %pi, i32 3
store i64 %ia1ap2, ptr %pia1ap2
; Fold strtoll(a[1].b + 3, 0, 0, ptr null, i32 0) to 4.
%pa1bp3 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 1, i64 3
%ia1bp3 = call i64 @strtoll(ptr %pa1bp3, ptr null, i32 0)
%pia1bp3 = getelementptr i64, ptr %pi, i32 4
store i64 %ia1bp3, ptr %pia1bp3
; Fold strtoll(a[1].c + 4, 0, 0, ptr null, i32 0) to 0.
%pa1cp4 = getelementptr [2 x %struct.A], ptr @a, i64 0, i64 1, i32 2, i64 4
%ia1cp4 = call i64 @strtoll(ptr %pa1cp4, ptr null, i32 0)
%pia1cp4 = getelementptr i64, ptr %pi, i32 5
store i64 %ia1cp4, ptr %pia1cp4
ret void
}
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