caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
4794bbffb228894de3ca0dad50fc027eb94f743e
clang-p2996/llvm/test/Transforms/InstCombine/atomic.ll
Nikita Popov aae5f8115a [Local] Consider atomic loads from constant global as dead 
Per the guidance in
https://llvm.org/docs/Atomics.html#atomics-and-ir-optimization,
an atomic load from a constant global can be dropped, as there can
be no stores to synchronize with. Any write to the constant global
would be UB.

IPSCCP will already drop such loads, but the main helper in Local
doesn't recognize this currently. This is motivated by D118387.

Differential Revision: https://reviews.llvm.org/D124241
2022-05-02 10:52:58 +02:00

462 lines
14 KiB
LLVM
Raw Blame History

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S < %s -passes=instcombine | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-apple-macosx10.7.0"
; Check transforms involving atomic operations
define i32 @test1(i32* %p) {
; CHECK-LABEL: @test1(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* [[P:%.*]] seq_cst, align 4
; CHECK-NEXT: [[Z:%.*]] = shl i32 [[X]], 1
; CHECK-NEXT: ret i32 [[Z]]
;
%x = load atomic i32, i32* %p seq_cst, align 4
%y = load i32, i32* %p, align 4
%z = add i32 %x, %y
ret i32 %z
}
define i32 @test2(i32* %p) {
; CHECK-LABEL: @test2(
; CHECK-NEXT: [[X:%.*]] = load volatile i32, i32* [[P:%.*]], align 4
; CHECK-NEXT: [[Y:%.*]] = load volatile i32, i32* [[P]], align 4
; CHECK-NEXT: [[Z:%.*]] = add i32 [[X]], [[Y]]
; CHECK-NEXT: ret i32 [[Z]]
;
%x = load volatile i32, i32* %p, align 4
%y = load volatile i32, i32* %p, align 4
%z = add i32 %x, %y
ret i32 %z
}
; The exact semantics of mixing volatile and non-volatile on the same
; memory location are a bit unclear, but conservatively, we know we don't
; want to remove the volatile.
define i32 @test3(i32* %p) {
; CHECK-LABEL: @test3(
; CHECK-NEXT: [[X:%.*]] = load volatile i32, i32* [[P:%.*]], align 4
; CHECK-NEXT: [[Z:%.*]] = shl i32 [[X]], 1
; CHECK-NEXT: ret i32 [[Z]]
;
%x = load volatile i32, i32* %p, align 4
%y = load i32, i32* %p, align 4
%z = add i32 %x, %y
ret i32 %z
}
; Forwarding from a stronger ordered atomic is fine
define i32 @test4(i32* %p) {
; CHECK-LABEL: @test4(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* [[P:%.*]] seq_cst, align 4
; CHECK-NEXT: [[Z:%.*]] = shl i32 [[X]], 1
; CHECK-NEXT: ret i32 [[Z]]
;
%x = load atomic i32, i32* %p seq_cst, align 4
%y = load atomic i32, i32* %p unordered, align 4
%z = add i32 %x, %y
ret i32 %z
}
; Forwarding from a non-atomic is not. (The earlier load
; could in priciple be promoted to atomic and then forwarded,
; but we can't just drop the atomic from the load.)
define i32 @test5(i32* %p) {
; CHECK-LABEL: @test5(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* [[P:%.*]] unordered, align 4
; CHECK-NEXT: [[Z:%.*]] = shl i32 [[X]], 1
; CHECK-NEXT: ret i32 [[Z]]
;
%x = load atomic i32, i32* %p unordered, align 4
%y = load i32, i32* %p, align 4
%z = add i32 %x, %y
ret i32 %z
}
; Forwarding atomic to atomic is fine
define i32 @test6(i32* %p) {
; CHECK-LABEL: @test6(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* [[P:%.*]] unordered, align 4
; CHECK-NEXT: [[Z:%.*]] = shl i32 [[X]], 1
; CHECK-NEXT: ret i32 [[Z]]
;
%x = load atomic i32, i32* %p unordered, align 4
%y = load atomic i32, i32* %p unordered, align 4
%z = add i32 %x, %y
ret i32 %z
}
; FIXME: we currently don't do anything for monotonic
define i32 @test7(i32* %p) {
; CHECK-LABEL: @test7(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* [[P:%.*]] seq_cst, align 4
; CHECK-NEXT: [[Y:%.*]] = load atomic i32, i32* [[P]] monotonic, align 4
; CHECK-NEXT: [[Z:%.*]] = add i32 [[X]], [[Y]]
; CHECK-NEXT: ret i32 [[Z]]
;
%x = load atomic i32, i32* %p seq_cst, align 4
%y = load atomic i32, i32* %p monotonic, align 4
%z = add i32 %x, %y
ret i32 %z
}
; FIXME: We could forward in racy code
define i32 @test8(i32* %p) {
; CHECK-LABEL: @test8(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* [[P:%.*]] seq_cst, align 4
; CHECK-NEXT: [[Y:%.*]] = load atomic i32, i32* [[P]] acquire, align 4
; CHECK-NEXT: [[Z:%.*]] = add i32 [[X]], [[Y]]
; CHECK-NEXT: ret i32 [[Z]]
;
%x = load atomic i32, i32* %p seq_cst, align 4
%y = load atomic i32, i32* %p acquire, align 4
%z = add i32 %x, %y
ret i32 %z
}
; An unordered access to null is still unreachable. There's no
; ordering imposed.
define i32 @test9() {
; CHECK-LABEL: @test9(
; CHECK-NEXT: store i32 poison, i32* null, align 4294967296
; CHECK-NEXT: ret i32 poison
;
%x = load atomic i32, i32* null unordered, align 4
ret i32 %x
}
define i32 @test9_no_null_opt() #0 {
; CHECK-LABEL: @test9_no_null_opt(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* null unordered, align 4294967296
; CHECK-NEXT: ret i32 [[X]]
;
%x = load atomic i32, i32* null unordered, align 4
ret i32 %x
}
; FIXME: Could also fold
define i32 @test10() {
; CHECK-LABEL: @test10(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* null monotonic, align 4294967296
; CHECK-NEXT: ret i32 [[X]]
;
%x = load atomic i32, i32* null monotonic, align 4
ret i32 %x
}
define i32 @test10_no_null_opt() #0 {
; CHECK-LABEL: @test10_no_null_opt(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* null monotonic, align 4294967296
; CHECK-NEXT: ret i32 [[X]]
;
%x = load atomic i32, i32* null monotonic, align 4
ret i32 %x
}
; Would this be legal to fold? Probably?
define i32 @test11() {
; CHECK-LABEL: @test11(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* null seq_cst, align 4294967296
; CHECK-NEXT: ret i32 [[X]]
;
%x = load atomic i32, i32* null seq_cst, align 4
ret i32 %x
}
define i32 @test11_no_null_opt() #0 {
; CHECK-LABEL: @test11_no_null_opt(
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* null seq_cst, align 4294967296
; CHECK-NEXT: ret i32 [[X]]
;
%x = load atomic i32, i32* null seq_cst, align 4
ret i32 %x
}
; An unordered access to null is still unreachable. There's no
; ordering imposed.
define i32 @test12() {
; CHECK-LABEL: @test12(
; CHECK-NEXT: store atomic i32 poison, i32* null unordered, align 4294967296
; CHECK-NEXT: ret i32 0
;
store atomic i32 0, i32* null unordered, align 4
ret i32 0
}
define i32 @test12_no_null_opt() #0 {
; CHECK-LABEL: @test12_no_null_opt(
; CHECK-NEXT: store atomic i32 0, i32* null unordered, align 4294967296
; CHECK-NEXT: ret i32 0
;
store atomic i32 0, i32* null unordered, align 4
ret i32 0
}
; FIXME: Could also fold
define i32 @test13() {
; CHECK-LABEL: @test13(
; CHECK-NEXT: store atomic i32 0, i32* null monotonic, align 4294967296
; CHECK-NEXT: ret i32 0
;
store atomic i32 0, i32* null monotonic, align 4
ret i32 0
}
define i32 @test13_no_null_opt() #0 {
; CHECK-LABEL: @test13_no_null_opt(
; CHECK-NEXT: store atomic i32 0, i32* null monotonic, align 4294967296
; CHECK-NEXT: ret i32 0
;
store atomic i32 0, i32* null monotonic, align 4
ret i32 0
}
; Would this be legal to fold? Probably?
define i32 @test14() {
; CHECK-LABEL: @test14(
; CHECK-NEXT: store atomic i32 0, i32* null seq_cst, align 4294967296
; CHECK-NEXT: ret i32 0
;
store atomic i32 0, i32* null seq_cst, align 4
ret i32 0
}
define i32 @test14_no_null_opt() #0 {
; CHECK-LABEL: @test14_no_null_opt(
; CHECK-NEXT: store atomic i32 0, i32* null seq_cst, align 4294967296
; CHECK-NEXT: ret i32 0
;
store atomic i32 0, i32* null seq_cst, align 4
ret i32 0
}
@a = external global i32
@b = external global i32
define i32 @test15(i1 %cnd) {
; CHECK-LABEL: @test15(
; CHECK-NEXT: [[A_VAL:%.*]] = load atomic i32, i32* @a unordered, align 4
; CHECK-NEXT: [[B_VAL:%.*]] = load atomic i32, i32* @b unordered, align 4
; CHECK-NEXT: [[X:%.*]] = select i1 [[CND:%.*]], i32 [[A_VAL]], i32 [[B_VAL]]
; CHECK-NEXT: ret i32 [[X]]
;
%addr = select i1 %cnd, i32* @a, i32* @b
%x = load atomic i32, i32* %addr unordered, align 4
ret i32 %x
}
; FIXME: This would be legal to transform
define i32 @test16(i1 %cnd) {
; CHECK-LABEL: @test16(
; CHECK-NEXT: [[ADDR:%.*]] = select i1 [[CND:%.*]], i32* @a, i32* @b
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* [[ADDR]] monotonic, align 4
; CHECK-NEXT: ret i32 [[X]]
;
%addr = select i1 %cnd, i32* @a, i32* @b
%x = load atomic i32, i32* %addr monotonic, align 4
ret i32 %x
}
; FIXME: This would be legal to transform
define i32 @test17(i1 %cnd) {
; CHECK-LABEL: @test17(
; CHECK-NEXT: [[ADDR:%.*]] = select i1 [[CND:%.*]], i32* @a, i32* @b
; CHECK-NEXT: [[X:%.*]] = load atomic i32, i32* [[ADDR]] seq_cst, align 4
; CHECK-NEXT: ret i32 [[X]]
;
%addr = select i1 %cnd, i32* @a, i32* @b
%x = load atomic i32, i32* %addr seq_cst, align 4
ret i32 %x
}
define i32 @test22(i1 %cnd) {
; CHECK-LABEL: @test22(
; CHECK-NEXT: br i1 [[CND:%.*]], label [[BLOCK1:%.*]], label [[BLOCK2:%.*]]
; CHECK: block1:
; CHECK-NEXT: br label [[MERGE:%.*]]
; CHECK: block2:
; CHECK-NEXT: br label [[MERGE]]
; CHECK: merge:
; CHECK-NEXT: [[STOREMERGE:%.*]] = phi i32 [ 2, [[BLOCK2]] ], [ 1, [[BLOCK1]] ]
; CHECK-NEXT: store atomic i32 [[STOREMERGE]], i32* @a unordered, align 4
; CHECK-NEXT: ret i32 0
;
br i1 %cnd, label %block1, label %block2
block1:
store atomic i32 1, i32* @a unordered, align 4
br label %merge
block2:
store atomic i32 2, i32* @a unordered, align 4
br label %merge
merge:
ret i32 0
}
; TODO: probably also legal here
define i32 @test23(i1 %cnd) {
; CHECK-LABEL: @test23(
; CHECK-NEXT: br i1 [[CND:%.*]], label [[BLOCK1:%.*]], label [[BLOCK2:%.*]]
; CHECK: block1:
; CHECK-NEXT: store atomic i32 1, i32* @a monotonic, align 4
; CHECK-NEXT: br label [[MERGE:%.*]]
; CHECK: block2:
; CHECK-NEXT: store atomic i32 2, i32* @a monotonic, align 4
; CHECK-NEXT: br label [[MERGE]]
; CHECK: merge:
; CHECK-NEXT: ret i32 0
;
br i1 %cnd, label %block1, label %block2
block1:
store atomic i32 1, i32* @a monotonic, align 4
br label %merge
block2:
store atomic i32 2, i32* @a monotonic, align 4
br label %merge
merge:
ret i32 0
}
declare void @clobber()
define i32 @test18(float* %p) {
; CHECK-LABEL: @test18(
; CHECK-NEXT: [[X:%.*]] = load atomic float, float* [[P:%.*]] unordered, align 4
; CHECK-NEXT: call void @clobber()
; CHECK-NEXT: store atomic float [[X]], float* [[P]] unordered, align 4
; CHECK-NEXT: ret i32 0
;
%x = load atomic float, float* %p unordered, align 4
call void @clobber() ;; keep the load around
store atomic float %x, float* %p unordered, align 4
ret i32 0
}
; TODO: probably also legal in this case
define i32 @test19(float* %p) {
; CHECK-LABEL: @test19(
; CHECK-NEXT: [[X:%.*]] = load atomic float, float* [[P:%.*]] seq_cst, align 4
; CHECK-NEXT: call void @clobber()
; CHECK-NEXT: store atomic float [[X]], float* [[P]] seq_cst, align 4
; CHECK-NEXT: ret i32 0
;
%x = load atomic float, float* %p seq_cst, align 4
call void @clobber() ;; keep the load around
store atomic float %x, float* %p seq_cst, align 4
ret i32 0
}
define i32 @test20(i32** %p, i8* %v) {
; CHECK-LABEL: @test20(
; CHECK-NEXT: [[TMP1:%.*]] = bitcast i32** [[P:%.*]] to i8**
; CHECK-NEXT: store atomic i8* [[V:%.*]], i8** [[TMP1]] unordered, align 4
; CHECK-NEXT: ret i32 0
;
%cast = bitcast i8* %v to i32*
store atomic i32* %cast, i32** %p unordered, align 4
ret i32 0
}
define i32 @test21(i32** %p, i8* %v) {
; CHECK-LABEL: @test21(
; CHECK-NEXT: [[CAST:%.*]] = bitcast i8* [[V:%.*]] to i32*
; CHECK-NEXT: store atomic i32* [[CAST]], i32** [[P:%.*]] monotonic, align 4
; CHECK-NEXT: ret i32 0
;
%cast = bitcast i8* %v to i32*
store atomic i32* %cast, i32** %p monotonic, align 4
ret i32 0
}
define void @pr27490a(i8** %p1, i8** %p2) {
; CHECK-LABEL: @pr27490a(
; CHECK-NEXT: [[L:%.*]] = load i8*, i8** [[P1:%.*]], align 8
; CHECK-NEXT: store volatile i8* [[L]], i8** [[P2:%.*]], align 8
; CHECK-NEXT: ret void
;
%l = load i8*, i8** %p1
store volatile i8* %l, i8** %p2
ret void
}
define void @pr27490b(i8** %p1, i8** %p2) {
; CHECK-LABEL: @pr27490b(
; CHECK-NEXT: [[L:%.*]] = load i8*, i8** [[P1:%.*]], align 8
; CHECK-NEXT: store atomic i8* [[L]], i8** [[P2:%.*]] seq_cst, align 8
; CHECK-NEXT: ret void
;
%l = load i8*, i8** %p1
store atomic i8* %l, i8** %p2 seq_cst, align 8
ret void
}
;; At the moment, we can't form atomic vectors by folding since these are
;; not representable in the IR. This was pr29121. The right long term
;; solution is to extend the IR to handle this case.
define <2 x float> @no_atomic_vector_load(i64* %p) {
; CHECK-LABEL: @no_atomic_vector_load(
; CHECK-NEXT: [[LOAD:%.*]] = load atomic i64, i64* [[P:%.*]] unordered, align 8
; CHECK-NEXT: [[DOTCAST:%.*]] = bitcast i64 [[LOAD]] to <2 x float>
; CHECK-NEXT: ret <2 x float> [[DOTCAST]]
;
%load = load atomic i64, i64* %p unordered, align 8
%.cast = bitcast i64 %load to <2 x float>
ret <2 x float> %.cast
}
define void @no_atomic_vector_store(<2 x float> %p, i8* %p2) {
; CHECK-LABEL: @no_atomic_vector_store(
; CHECK-NEXT: [[TMP1:%.*]] = bitcast <2 x float> [[P:%.*]] to i64
; CHECK-NEXT: [[TMP2:%.*]] = bitcast i8* [[P2:%.*]] to i64*
; CHECK-NEXT: store atomic i64 [[TMP1]], i64* [[TMP2]] unordered, align 8
; CHECK-NEXT: ret void
;
%1 = bitcast <2 x float> %p to i64
%2 = bitcast i8* %p2 to i64*
store atomic i64 %1, i64* %2 unordered, align 8
ret void
}
@c = constant i32 42
@g = global i32 42
define i32 @atomic_load_from_constant_global() {
; CHECK-LABEL: @atomic_load_from_constant_global(
; CHECK-NEXT: ret i32 42
;
%v = load atomic i32, i32* @c seq_cst, align 4
ret i32 %v
}
define i8 @atomic_load_from_constant_global_bitcast() {
; CHECK-LABEL: @atomic_load_from_constant_global_bitcast(
; CHECK-NEXT: ret i8 42
;
%v = load atomic i8, i8* bitcast (i32* @c to i8*) seq_cst, align 1
ret i8 %v
}
define void @atomic_load_from_non_constant_global() {
; CHECK-LABEL: @atomic_load_from_non_constant_global(
; CHECK-NEXT: [[TMP1:%.*]] = load atomic i32, i32* @g seq_cst, align 4
; CHECK-NEXT: ret void
;
load atomic i32, i32* @g seq_cst, align 4
ret void
}
define void @volatile_load_from_constant_global() {
; CHECK-LABEL: @volatile_load_from_constant_global(
; CHECK-NEXT: [[TMP1:%.*]] = load volatile i32, i32* @c, align 4
; CHECK-NEXT: ret void
;
load volatile i32, i32* @c, align 4
ret void
}
attributes #0 = { null_pointer_is_valid }
Reference in New Issue View Git Blame Copy Permalink