caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
dda73336ad22bd0b5ecda17040c50fb10fcbe5fb
clang-p2996/llvm/test/Transforms/InstCombine/select-gep.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

259 lines
10 KiB
LLVM
Raw Blame History

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -passes=instcombine -S | FileCheck %s
define ptr @test1a(ptr %p, ptr %q) {
; CHECK-LABEL: @test1a(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt ptr [[P:%.*]], [[Q:%.*]]
; CHECK-NEXT: [[SELECT_V:%.*]] = select i1 [[CMP]], ptr [[P]], ptr [[Q]]
; CHECK-NEXT: [[SELECT:%.*]] = getelementptr i8, ptr [[SELECT_V]], i64 16
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr i32, ptr %p, i64 4
%gep2 = getelementptr i32, ptr %q, i64 4
%cmp = icmp ugt ptr %p, %q
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
define ptr @test1b(ptr %p, ptr %q) {
; CHECK-LABEL: @test1b(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt ptr [[P:%.*]], [[Q:%.*]]
; CHECK-NEXT: [[SELECT_V:%.*]] = select i1 [[CMP]], ptr [[P]], ptr [[Q]]
; CHECK-NEXT: [[SELECT:%.*]] = getelementptr i8, ptr [[SELECT_V]], i64 16
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr inbounds i32, ptr %p, i64 4
%gep2 = getelementptr i32, ptr %q, i64 4
%cmp = icmp ugt ptr %p, %q
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
define ptr @test1c(ptr %p, ptr %q) {
; CHECK-LABEL: @test1c(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt ptr [[P:%.*]], [[Q:%.*]]
; CHECK-NEXT: [[SELECT_V:%.*]] = select i1 [[CMP]], ptr [[P]], ptr [[Q]]
; CHECK-NEXT: [[SELECT:%.*]] = getelementptr i8, ptr [[SELECT_V]], i64 16
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr i32, ptr %p, i64 4
%gep2 = getelementptr inbounds i32, ptr %q, i64 4
%cmp = icmp ugt ptr %p, %q
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
define ptr @test1d(ptr %p, ptr %q) {
; CHECK-LABEL: @test1d(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt ptr [[P:%.*]], [[Q:%.*]]
; CHECK-NEXT: [[SELECT_V:%.*]] = select i1 [[CMP]], ptr [[P]], ptr [[Q]]
; CHECK-NEXT: [[SELECT:%.*]] = getelementptr inbounds i8, ptr [[SELECT_V]], i64 16
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr inbounds i32, ptr %p, i64 4
%gep2 = getelementptr inbounds i32, ptr %q, i64 4
%cmp = icmp ugt ptr %p, %q
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
define ptr @test2(ptr %p, i64 %x, i64 %y) {
; CHECK-LABEL: @test2(
; CHECK-NEXT: [[SELECT_V:%.*]] = call i64 @llvm.umax.i64(i64 [[X:%.*]], i64 [[Y:%.*]])
; CHECK-NEXT: [[SELECT:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[SELECT_V]]
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr inbounds i32, ptr %p, i64 %x
%gep2 = getelementptr inbounds i32, ptr %p, i64 %y
%cmp = icmp ugt i64 %x, %y
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
; PR50183
define ptr @test2a(ptr %p, i64 %x, i64 %y) {
; CHECK-LABEL: @test2a(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SELECT_IDX:%.*]] = select i1 [[CMP]], i64 [[X]], i64 0
; CHECK-NEXT: [[SELECT:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[SELECT_IDX]]
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep = getelementptr inbounds i32, ptr %p, i64 %x
%cmp = icmp ugt i64 %x, %y
%select = select i1 %cmp, ptr %gep, ptr %p
ret ptr %select
}
; PR50183
define ptr @test2b(ptr %p, i64 %x, i64 %y) {
; CHECK-LABEL: @test2b(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[SELECT_IDX:%.*]] = select i1 [[CMP]], i64 0, i64 [[X]]
; CHECK-NEXT: [[SELECT:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[SELECT_IDX]]
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep = getelementptr inbounds i32, ptr %p, i64 %x
%cmp = icmp ugt i64 %x, %y
%select = select i1 %cmp, ptr %p, ptr %gep
ret ptr %select
}
; PR51069
define ptr @test2c(ptr %p, i64 %x, i64 %y) {
; CHECK-LABEL: @test2c(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[X:%.*]]
; CHECK-NEXT: [[ICMP:%.*]] = icmp ugt i64 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[SEL_IDX:%.*]] = select i1 [[ICMP]], i64 0, i64 24
; CHECK-NEXT: [[SEL:%.*]] = getelementptr inbounds i8, ptr [[GEP1]], i64 [[SEL_IDX]]
; CHECK-NEXT: ret ptr [[SEL]]
;
%gep1 = getelementptr inbounds i32, ptr %p, i64 %x
%gep2 = getelementptr inbounds i32, ptr %gep1, i64 6
%icmp = icmp ugt i64 %x, %y
%sel = select i1 %icmp, ptr %gep1, ptr %gep2
ret ptr %sel
}
; PR51069
define ptr @test2d(ptr %p, i64 %x, i64 %y) {
; CHECK-LABEL: @test2d(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[X:%.*]]
; CHECK-NEXT: [[ICMP:%.*]] = icmp ugt i64 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[SEL_IDX:%.*]] = select i1 [[ICMP]], i64 24, i64 0
; CHECK-NEXT: [[SEL:%.*]] = getelementptr inbounds i8, ptr [[GEP1]], i64 [[SEL_IDX]]
; CHECK-NEXT: ret ptr [[SEL]]
;
%gep1 = getelementptr inbounds i32, ptr %p, i64 %x
%gep2 = getelementptr inbounds i32, ptr %gep1, i64 6
%icmp = icmp ugt i64 %x, %y
%sel = select i1 %icmp, ptr %gep2, ptr %gep1
ret ptr %sel
}
; Three (or more) operand GEPs are currently expected to not be optimised,
; though they could be in principle.
define ptr @test3a(ptr %p, i64 %x, i64 %y) {
; CHECK-LABEL: @test3a(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds [4 x i32], ptr [[P:%.*]], i64 2, i64 [[X:%.*]]
; CHECK-NEXT: [[GEP2:%.*]] = getelementptr inbounds [4 x i32], ptr [[P]], i64 2, i64 [[Y:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[X]], [[Y]]
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[CMP]], ptr [[GEP1]], ptr [[GEP2]]
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr inbounds [4 x i32], ptr %p, i64 2, i64 %x
%gep2 = getelementptr inbounds [4 x i32], ptr %p, i64 2, i64 %y
%cmp = icmp ugt i64 %x, %y
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
define ptr @test3b(ptr %p, ptr %q, i64 %x, i64 %y) {
; CHECK-LABEL: @test3b(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds [4 x i32], ptr [[P:%.*]], i64 2, i64 [[X:%.*]]
; CHECK-NEXT: [[GEP2:%.*]] = getelementptr inbounds [4 x i32], ptr [[Q:%.*]], i64 2, i64 [[X]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[CMP]], ptr [[GEP1]], ptr [[GEP2]]
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr inbounds [4 x i32], ptr %p, i64 2, i64 %x
%gep2 = getelementptr inbounds [4 x i32], ptr %q, i64 2, i64 %x
%cmp = icmp ugt i64 %x, %y
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
define ptr @test3c(ptr %p, ptr %q, i64 %x, i64 %y) {
; CHECK-LABEL: @test3c(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds [4 x i32], ptr [[P:%.*]], i64 [[X:%.*]], i64 2
; CHECK-NEXT: [[GEP2:%.*]] = getelementptr inbounds i32, ptr [[Q:%.*]], i64 [[X]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[CMP]], ptr [[GEP1]], ptr [[GEP2]]
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr inbounds [4 x i32], ptr %p, i64 %x, i64 2
%gep2 = getelementptr inbounds i32, ptr %q, i64 %x
%cmp = icmp ugt i64 %x, %y
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
define ptr @test3d(ptr %p, ptr %q, i64 %x, i64 %y) {
; CHECK-LABEL: @test3d(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[X:%.*]]
; CHECK-NEXT: [[GEP2:%.*]] = getelementptr inbounds [4 x i32], ptr [[Q:%.*]], i64 [[X]], i64 2
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[CMP]], ptr [[GEP1]], ptr [[GEP2]]
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr inbounds i32, ptr %p, i64 %x
%gep2 = getelementptr inbounds [4 x i32], ptr %q, i64 %x, i64 2
%cmp = icmp ugt i64 %x, %y
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
; Shouldn't be optimised as it would mean introducing an extra select
define ptr @test4(ptr %p, ptr %q, i64 %x, i64 %y) {
; CHECK-LABEL: @test4(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[X:%.*]]
; CHECK-NEXT: [[GEP2:%.*]] = getelementptr inbounds i32, ptr [[Q:%.*]], i64 [[Y:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i64 [[X]], [[Y]]
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[CMP]], ptr [[GEP1]], ptr [[GEP2]]
; CHECK-NEXT: ret ptr [[SELECT]]
;
%gep1 = getelementptr inbounds i32, ptr %p, i64 %x
%gep2 = getelementptr inbounds i32, ptr %q, i64 %y
%cmp = icmp ugt i64 %x, %y
%select = select i1 %cmp, ptr %gep1, ptr %gep2
ret ptr %select
}
; We cannot create a select with a vector condition but scalar operands.
define <2 x ptr> @test5(ptr %p1, ptr %p2, <2 x i64> %idx, <2 x i1> %cc) {
; CHECK-LABEL: @test5(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr i64, ptr [[P1:%.*]], <2 x i64> [[IDX:%.*]]
; CHECK-NEXT: [[GEP2:%.*]] = getelementptr i64, ptr [[P2:%.*]], <2 x i64> [[IDX]]
; CHECK-NEXT: [[SELECT:%.*]] = select <2 x i1> [[CC:%.*]], <2 x ptr> [[GEP1]], <2 x ptr> [[GEP2]]
; CHECK-NEXT: ret <2 x ptr> [[SELECT]]
;
%gep1 = getelementptr i64, ptr %p1, <2 x i64> %idx
%gep2 = getelementptr i64, ptr %p2, <2 x i64> %idx
%select = select <2 x i1> %cc, <2 x ptr> %gep1, <2 x ptr> %gep2
ret <2 x ptr> %select
}
; PR51069 - multiple uses
define ptr @test6(ptr %p, i64 %x, i64 %y) {
; CHECK-LABEL: @test6(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[X:%.*]]
; CHECK-NEXT: [[ICMP:%.*]] = icmp ugt i64 [[X]], [[Y:%.*]]
; CHECK-NEXT: [[SEL_IDX:%.*]] = select i1 [[ICMP]], i64 [[Y]], i64 0
; CHECK-NEXT: [[SEL:%.*]] = getelementptr inbounds i32, ptr [[GEP1]], i64 [[SEL_IDX]]
; CHECK-NEXT: call void @use_i32p(ptr [[GEP1]])
; CHECK-NEXT: ret ptr [[SEL]]
;
%gep1 = getelementptr inbounds i32, ptr %p, i64 %x
%gep2 = getelementptr inbounds i32, ptr %gep1, i64 %y
%icmp = icmp ugt i64 %x, %y
%sel = select i1 %icmp, ptr %gep2, ptr %gep1
call void @use_i32p(ptr %gep1)
ret ptr %sel
}
declare void @use_i32p(ptr)
; We cannot create a select-with-idx with a vector condition but scalar idx.
define <2 x ptr> @test7(<2 x ptr> %p1, i64 %idx, <2 x i1> %cc) {
; CHECK-LABEL: @test7(
; CHECK-NEXT: [[GEP:%.*]] = getelementptr i64, <2 x ptr> [[P1:%.*]], i64 [[IDX:%.*]]
; CHECK-NEXT: [[SELECT:%.*]] = select <2 x i1> [[CC:%.*]], <2 x ptr> [[P1]], <2 x ptr> [[GEP]]
; CHECK-NEXT: ret <2 x ptr> [[SELECT]]
;
%gep = getelementptr i64, <2 x ptr> %p1, i64 %idx
%select = select <2 x i1> %cc, <2 x ptr> %p1, <2 x ptr> %gep
ret <2 x ptr> %select
}
Reference in New Issue View Git Blame Copy Permalink