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clang-p2996/llvm/test/Transforms/InstCombine/load.ll
Arthur Eubanks 05392466f0 Reland [IR] Increase max alignment to 4GB 
Currently the max alignment representable is 1GB, see D108661.
Setting the align of an object to 4GB is desirable in some cases to make sure the lower 32 bits are clear which can be used for some optimizations, e.g. https://crbug.com/1016945.

This uses an extra bit in instructions that carry an alignment. We can store 15 bits of "free" information, and with this change some instructions (e.g. AtomicCmpXchgInst) use 14 bits.
We can increase the max alignment representable above 4GB (up to 2^62) since we're only using 33 of the 64 values, but I've just limited it to 4GB for now.

The one place we have to update the bitcode format is for the alloca instruction. It stores its alignment into 5 bits of a 32 bit bitfield. I've added another field which is 8 bits and should be future proof for a while. For backward compatibility, we check if the old field has a value and use that, otherwise use the new field.

Updating clang's max allowed alignment will come in a future patch.

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D110451
2021-10-06 13:29:23 -07:00

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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -instcombine -S < %s | FileCheck %s
; RUN: opt -passes=instcombine -S < %s | FileCheck %s
target datalayout = "e-m:e-p:64:64:64-i64:64-f80:128-n8:16:32:64-S128-ni:1"
@X = constant i32 42 ; <i32*> [#uses=2]
@X2 = constant i32 47 ; <i32*> [#uses=1]
@Y = constant [2 x { i32, float }] [ { i32, float } { i32 12, float 1.000000e+00 }, { i32, float } { i32 37, float 0x3FF3B2FEC0000000 } ] ; <[2 x { i32, float }]*> [#uses=2]
@Z = constant [2 x { i32, float }] zeroinitializer ; <[2 x { i32, float }]*> [#uses=1]
@GLOBAL = internal constant [4 x i32] zeroinitializer
define i32 @test1() {
; CHECK-LABEL: @test1(
; CHECK-NEXT: ret i32 42
;
%B = load i32, i32* @X ; <i32> [#uses=1]
ret i32 %B
}
define float @test2() {
; CHECK-LABEL: @test2(
; CHECK-NEXT: ret float 0x3FF3B2FEC0000000
;
%A = getelementptr [2 x { i32, float }], [2 x { i32, float }]* @Y, i64 0, i64 1, i32 1 ; <float*> [#uses=1]
%B = load float, float* %A ; <float> [#uses=1]
ret float %B
}
define i32 @test3() {
; CHECK-LABEL: @test3(
; CHECK-NEXT: ret i32 12
;
%A = getelementptr [2 x { i32, float }], [2 x { i32, float }]* @Y, i64 0, i64 0, i32 0 ; <i32*> [#uses=1]
%B = load i32, i32* %A ; <i32> [#uses=1]
ret i32 %B
}
define i32 @test4() {
; CHECK-LABEL: @test4(
; CHECK-NEXT: ret i32 0
;
%A = getelementptr [2 x { i32, float }], [2 x { i32, float }]* @Z, i64 0, i64 1, i32 0 ; <i32*> [#uses=1]
%B = load i32, i32* %A ; <i32> [#uses=1]
ret i32 %B
}
define i32 @test5(i1 %C) {
; CHECK-LABEL: @test5(
; CHECK-NEXT: [[Z:%.*]] = select i1 [[C:%.*]], i32 42, i32 47
; CHECK-NEXT: ret i32 [[Z]]
;
%Y = select i1 %C, i32* @X, i32* @X2 ; <i32*> [#uses=1]
%Z = load i32, i32* %Y ; <i32> [#uses=1]
ret i32 %Z
}
define i32 @load_gep_null_inbounds(i64 %X) {
; CHECK-LABEL: @load_gep_null_inbounds(
; CHECK-NEXT: store i32 poison, i32* null, align 4294967296
; CHECK-NEXT: ret i32 poison
;
%V = getelementptr inbounds i32, i32* null, i64 %X
%R = load i32, i32* %V
ret i32 %R
}
define i32 @load_gep_null_not_inbounds(i64 %X) {
; CHECK-LABEL: @load_gep_null_not_inbounds(
; CHECK-NEXT: store i32 poison, i32* null, align 4294967296
; CHECK-NEXT: ret i32 poison
;
%V = getelementptr i32, i32* null, i64 %X
%R = load i32, i32* %V
ret i32 %R
}
define i32 @test7_no_null_opt(i32 %X) #0 {
; CHECK-LABEL: @test7_no_null_opt(
; CHECK-NEXT: [[TMP1:%.*]] = sext i32 [[X:%.*]] to i64
; CHECK-NEXT: [[V:%.*]] = getelementptr i32, i32* null, i64 [[TMP1]]
; CHECK-NEXT: [[R:%.*]] = load i32, i32* [[V]], align 4
; CHECK-NEXT: ret i32 [[R]]
;
%V = getelementptr i32, i32* null, i32 %X ; <i32*> [#uses=1]
%R = load i32, i32* %V ; <i32> [#uses=1]
ret i32 %R
}
attributes #0 = { null_pointer_is_valid }
define i32 @test8(i32* %P) {
; CHECK-LABEL: @test8(
; CHECK-NEXT: store i32 1, i32* [[P:%.*]], align 4
; CHECK-NEXT: ret i32 1
;
store i32 1, i32* %P
%X = load i32, i32* %P ; <i32> [#uses=1]
ret i32 %X
}
define i32 @test9(i32* %P) {
; CHECK-LABEL: @test9(
; CHECK-NEXT: ret i32 0
;
%X = load i32, i32* %P ; <i32> [#uses=1]
%Y = load i32, i32* %P ; <i32> [#uses=1]
%Z = sub i32 %X, %Y ; <i32> [#uses=1]
ret i32 %Z
}
define i32 @test10(i1 %C.upgrd.1, i32* %P, i32* %Q) {
; CHECK-LABEL: @test10(
; CHECK-NEXT: br i1 [[C_UPGRD_1:%.*]], label [[T:%.*]], label [[F:%.*]]
; CHECK: T:
; CHECK-NEXT: store i32 1, i32* [[Q:%.*]], align 4
; CHECK-NEXT: br label [[C:%.*]]
; CHECK: F:
; CHECK-NEXT: br label [[C]]
; CHECK: C:
; CHECK-NEXT: store i32 0, i32* [[P:%.*]], align 4
; CHECK-NEXT: ret i32 0
;
br i1 %C.upgrd.1, label %T, label %F
T: ; preds = %0
store i32 1, i32* %Q
store i32 0, i32* %P
br label %C
F: ; preds = %0
store i32 0, i32* %P
br label %C
C: ; preds = %F, %T
%V = load i32, i32* %P ; <i32> [#uses=1]
ret i32 %V
}
define double @test11(double* %p) {
; CHECK-LABEL: @test11(
; CHECK-NEXT: [[T0:%.*]] = getelementptr double, double* [[P:%.*]], i64 1
; CHECK-NEXT: store double 2.000000e+00, double* [[T0]], align 8
; CHECK-NEXT: ret double 2.000000e+00
;
%t0 = getelementptr double, double* %p, i32 1
store double 2.0, double* %t0
%t1 = getelementptr double, double* %p, i32 1
%x = load double, double* %t1
ret double %x
}
define i32 @test12(i32* %P) {
; CHECK-LABEL: @test12(
; CHECK-NEXT: ret i32 123
;
%A = alloca i32
store i32 123, i32* %A
; Cast the result of the load not the source
%Q = bitcast i32* %A to i32*
%V = load i32, i32* %Q
ret i32 %V
}
define <16 x i8> @test13(<2 x i64> %x) {
; CHECK-LABEL: @test13(
; CHECK-NEXT: ret <16 x i8> zeroinitializer
;
%tmp = load <16 x i8>, <16 x i8>* bitcast ([4 x i32]* @GLOBAL to <16 x i8>*)
ret <16 x i8> %tmp
}
; This test must not have the store of %x forwarded to the load -- there is an
; intervening store if %y. However, the intervening store occurs with a different
; type and size and to a different pointer value. This is ensuring that none of
; those confuse the analysis into thinking that the second store does not alias
; the first.
define i8 @test14(i8 %x, i32 %y) {
; CHECK-LABEL: @test14(
; CHECK-NEXT: [[A:%.*]] = alloca i32, align 4
; CHECK-NEXT: [[A_I8:%.*]] = bitcast i32* [[A]] to i8*
; CHECK-NEXT: store i8 [[X:%.*]], i8* [[A_I8]], align 4
; CHECK-NEXT: store i32 [[Y:%.*]], i32* [[A]], align 4
; CHECK-NEXT: [[R:%.*]] = load i8, i8* [[A_I8]], align 4
; CHECK-NEXT: ret i8 [[R]]
;
%a = alloca i32
%a.i8 = bitcast i32* %a to i8*
store i8 %x, i8* %a.i8
store i32 %y, i32* %a
%r = load i8, i8* %a.i8
ret i8 %r
}
@test15_global = external global i32
; Same test as @test14 essentially, but using a global instead of an alloca.
define i8 @test15(i8 %x, i32 %y) {
; CHECK-LABEL: @test15(
; CHECK-NEXT: store i8 [[X:%.*]], i8* bitcast (i32* @test15_global to i8*), align 4
; CHECK-NEXT: store i32 [[Y:%.*]], i32* @test15_global, align 4
; CHECK-NEXT: [[R:%.*]] = load i8, i8* bitcast (i32* @test15_global to i8*), align 4
; CHECK-NEXT: ret i8 [[R]]
;
%g.i8 = bitcast i32* @test15_global to i8*
store i8 %x, i8* %g.i8
store i32 %y, i32* @test15_global
%r = load i8, i8* %g.i8
ret i8 %r
}
; Check that we canonicalize loads which are only stored to use integer types
; when there is a valid integer type.
define void @test16(i8* %x, i8* %a, i8* %b, i8* %c) {
; CHECK-LABEL: @test16(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[X_CAST:%.*]] = bitcast i8* [[X:%.*]] to float*
; CHECK-NEXT: [[A_CAST:%.*]] = bitcast i8* [[A:%.*]] to float*
; CHECK-NEXT: [[B_CAST:%.*]] = bitcast i8* [[B:%.*]] to float*
; CHECK-NEXT: [[X1:%.*]] = load float, float* [[X_CAST]], align 4
; CHECK-NEXT: store float [[X1]], float* [[A_CAST]], align 4
; CHECK-NEXT: store float [[X1]], float* [[B_CAST]], align 4
; CHECK-NEXT: [[X2:%.*]] = load float, float* [[X_CAST]], align 4
; CHECK-NEXT: store float [[X2]], float* [[B_CAST]], align 4
; CHECK-NEXT: [[TMP0:%.*]] = bitcast i8* [[C:%.*]] to float*
; CHECK-NEXT: store float [[X2]], float* [[TMP0]], align 4
; CHECK-NEXT: ret void
;
entry:
%x.cast = bitcast i8* %x to float*
%a.cast = bitcast i8* %a to float*
%b.cast = bitcast i8* %b to float*
%c.cast = bitcast i8* %c to i32*
%x1 = load float, float* %x.cast
store float %x1, float* %a.cast
store float %x1, float* %b.cast
%x2 = load float, float* %x.cast
store float %x2, float* %b.cast
%x2.cast = bitcast float %x2 to i32
store i32 %x2.cast, i32* %c.cast
ret void
}
define void @test16-vect(i8* %x, i8* %a, i8* %b, i8* %c) {
; CHECK-LABEL: @test16-vect(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[X_CAST:%.*]] = bitcast i8* [[X:%.*]] to <4 x i8>*
; CHECK-NEXT: [[A_CAST:%.*]] = bitcast i8* [[A:%.*]] to <4 x i8>*
; CHECK-NEXT: [[B_CAST:%.*]] = bitcast i8* [[B:%.*]] to <4 x i8>*
; CHECK-NEXT: [[X1:%.*]] = load <4 x i8>, <4 x i8>* [[X_CAST]], align 4
; CHECK-NEXT: store <4 x i8> [[X1]], <4 x i8>* [[A_CAST]], align 4
; CHECK-NEXT: store <4 x i8> [[X1]], <4 x i8>* [[B_CAST]], align 4
; CHECK-NEXT: [[X2:%.*]] = load <4 x i8>, <4 x i8>* [[X_CAST]], align 4
; CHECK-NEXT: store <4 x i8> [[X2]], <4 x i8>* [[B_CAST]], align 4
; CHECK-NEXT: [[TMP0:%.*]] = bitcast i8* [[C:%.*]] to <4 x i8>*
; CHECK-NEXT: store <4 x i8> [[X2]], <4 x i8>* [[TMP0]], align 4
; CHECK-NEXT: ret void
;
entry:
%x.cast = bitcast i8* %x to <4 x i8>*
%a.cast = bitcast i8* %a to <4 x i8>*
%b.cast = bitcast i8* %b to <4 x i8>*
%c.cast = bitcast i8* %c to i32*
%x1 = load <4 x i8>, <4 x i8>* %x.cast
store <4 x i8> %x1, <4 x i8>* %a.cast
store <4 x i8> %x1, <4 x i8>* %b.cast
%x2 = load <4 x i8>, <4 x i8>* %x.cast
store <4 x i8> %x2, <4 x i8>* %b.cast
%x2.cast = bitcast <4 x i8> %x2 to i32
store i32 %x2.cast, i32* %c.cast
ret void
}
; Check that in cases similar to @test16 we don't try to rewrite a load when
; its only use is a store but it is used as the pointer to that store rather
; than the value.
define void @test17(i8** %x, i8 %y) {
; CHECK-LABEL: @test17(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[X_LOAD:%.*]] = load i8*, i8** [[X:%.*]], align 8
; CHECK-NEXT: store i8 [[Y:%.*]], i8* [[X_LOAD]], align 1
; CHECK-NEXT: ret void
;
entry:
%x.load = load i8*, i8** %x
store i8 %y, i8* %x.load
ret void
}
; Check that we don't try change the type of the load by inserting a bitcast
; generating invalid IR.
%swift.error = type opaque
declare void @useSwiftError(%swift.error** swifterror)
define void @test18(%swift.error** swifterror %err) {
; CHECK-LABEL: @test18(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SWIFTERROR:%.*]] = alloca swifterror %swift.error*, align 8
; CHECK-NEXT: store %swift.error* null, %swift.error** [[SWIFTERROR]], align 8
; CHECK-NEXT: call void @useSwiftError(%swift.error** nonnull swifterror [[SWIFTERROR]])
; CHECK-NEXT: [[ERR_RES:%.*]] = load %swift.error*, %swift.error** [[SWIFTERROR]], align 8
; CHECK-NEXT: store %swift.error* [[ERR_RES]], %swift.error** [[ERR:%.*]], align 8
; CHECK-NEXT: ret void
;
entry:
%swifterror = alloca swifterror %swift.error*, align 8
store %swift.error* null, %swift.error** %swifterror, align 8
call void @useSwiftError(%swift.error** nonnull swifterror %swifterror)
%err.res = load %swift.error*, %swift.error** %swifterror, align 8
store %swift.error* %err.res, %swift.error** %err, align 8
ret void
}
; Make sure we preseve the type of the store to a swifterror pointer.
declare void @initi8(i8**)
define void @test19(%swift.error** swifterror %err) {
; CHECK-LABEL: @test19(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP:%.*]] = alloca i8*, align 8
; CHECK-NEXT: call void @initi8(i8** nonnull [[TMP]])
; CHECK-NEXT: [[SWIFTERROR:%.*]] = bitcast i8** [[TMP]] to %swift.error**
; CHECK-NEXT: [[ERR_RES:%.*]] = load %swift.error*, %swift.error** [[SWIFTERROR]], align 8
; CHECK-NEXT: store %swift.error* [[ERR_RES]], %swift.error** [[ERR:%.*]], align 8
; CHECK-NEXT: ret void
;
entry:
%tmp = alloca i8*, align 8
call void @initi8(i8** %tmp)
%swifterror = bitcast i8** %tmp to %swift.error**
%err.res = load %swift.error*, %swift.error** %swifterror, align 8
store %swift.error* %err.res, %swift.error** %err, align 8
ret void
}
; Make sure we don't canonicalize accesses to scalable vectors.
define void @test20(<vscale x 4 x i8>* %x, <vscale x 4 x i8>* %y) {
; CHECK-LABEL: @test20(
; CHECK-NEXT: [[X_LOAD:%.*]] = load <vscale x 4 x i8>, <vscale x 4 x i8>* [[X:%.*]], align 1
; CHECK-NEXT: store <vscale x 4 x i8> [[X_LOAD]], <vscale x 4 x i8>* [[Y:%.*]], align 1
; CHECK-NEXT: ret void
;
%x.load = load <vscale x 4 x i8>, <vscale x 4 x i8>* %x, align 1
store <vscale x 4 x i8> %x.load, <vscale x 4 x i8>* %y, align 1
ret void
}
; Check that non-integral pointers are not coverted using inttoptr
declare void @use(i8*)
declare void @use.p1(i8 addrspace(1)*)
define i64 @test21(i64* %P) {
; CHECK-LABEL: @test21(
; CHECK-NEXT: [[X:%.*]] = load i64, i64* [[P:%.*]], align 8
; CHECK-NEXT: [[Y_CAST:%.*]] = inttoptr i64 [[X]] to i8*
; CHECK-NEXT: call void @use(i8* [[Y_CAST]])
; CHECK-NEXT: ret i64 [[X]]
;
%P.ptr = bitcast i64* %P to i8**
%X = load i64, i64* %P
%Y = load i8*, i8** %P.ptr
call void @use(i8* %Y)
ret i64 %X
}
define i64 @test22(i64* %P) {
; CHECK-LABEL: @test22(
; CHECK-NEXT: [[P_PTR:%.*]] = bitcast i64* [[P:%.*]] to i8 addrspace(1)**
; CHECK-NEXT: [[X:%.*]] = load i64, i64* [[P]], align 8
; CHECK-NEXT: [[Y:%.*]] = load i8 addrspace(1)*, i8 addrspace(1)** [[P_PTR]], align 8
; CHECK-NEXT: call void @use.p1(i8 addrspace(1)* [[Y]])
; CHECK-NEXT: ret i64 [[X]]
;
%P.ptr = bitcast i64* %P to i8 addrspace(1)**
%X = load i64, i64* %P
%Y = load i8 addrspace(1)*, i8 addrspace(1)** %P.ptr
call void @use.p1(i8 addrspace(1)* %Y)
ret i64 %X
}
declare void @use.v2.p0(<2 x i8*>)
declare void @use.v2.p1(<2 x i8 addrspace(1)*>)
define <2 x i64> @test23(<2 x i64>* %P) {
; CHECK-LABEL: @test23(
; CHECK-NEXT: [[P_PTR:%.*]] = bitcast <2 x i64>* [[P:%.*]] to <2 x i8*>*
; CHECK-NEXT: [[X:%.*]] = load <2 x i64>, <2 x i64>* [[P]], align 16
; CHECK-NEXT: [[Y:%.*]] = load <2 x i8*>, <2 x i8*>* [[P_PTR]], align 16
; CHECK-NEXT: call void @use.v2.p0(<2 x i8*> [[Y]])
; CHECK-NEXT: ret <2 x i64> [[X]]
;
%P.ptr = bitcast <2 x i64>* %P to <2 x i8*>*
%X = load <2 x i64>, <2 x i64>* %P
%Y = load <2 x i8*>, <2 x i8*>* %P.ptr
call void @use.v2.p0(<2 x i8*> %Y)
ret <2 x i64> %X
}
define <2 x i64> @test24(<2 x i64>* %P) {
; CHECK-LABEL: @test24(
; CHECK-NEXT: [[P_PTR:%.*]] = bitcast <2 x i64>* [[P:%.*]] to <2 x i8 addrspace(1)*>*
; CHECK-NEXT: [[X:%.*]] = load <2 x i64>, <2 x i64>* [[P]], align 16
; CHECK-NEXT: [[Y:%.*]] = load <2 x i8 addrspace(1)*>, <2 x i8 addrspace(1)*>* [[P_PTR]], align 16
; CHECK-NEXT: call void @use.v2.p1(<2 x i8 addrspace(1)*> [[Y]])
; CHECK-NEXT: ret <2 x i64> [[X]]
;
%P.ptr = bitcast <2 x i64>* %P to <2 x i8 addrspace(1)*>*
%X = load <2 x i64>, <2 x i64>* %P
%Y = load <2 x i8 addrspace(1)*>, <2 x i8 addrspace(1)*>* %P.ptr
call void @use.v2.p1(<2 x i8 addrspace(1)*> %Y)
ret <2 x i64> %X
}
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