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[CIR] Upstream zero init for global variables #133100

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merged 2 commits into from
Mar 31, 2025
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[CIR] Upstream zero init for global variables #133100

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b4aafe8
[CIR] Upstream zero init for global variables
AmrDeveloper Mar 26, 2025
6b84d15
Handle zero init attr for FP using isAnyFloatingPointType
AmrDeveloper Mar 27, 2025
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24 changes: 24 additions & 0 deletions clang/include/clang/CIR/Dialect/Builder/CIRBaseBuilder.h
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,30 @@ class CIRBaseBuilderTy : public mlir::OpBuilder {
return create<cir::ConstantOp>(loc, attr.getType(), attr);
}

mlir::TypedAttr getConstNullPtrAttr(mlir::Type t) {
assert(mlir::isa<cir::PointerType>(t) && "expected cir.ptr");
return getConstPtrAttr(t, 0);
}

mlir::TypedAttr getZeroAttr(mlir::Type t) {
return cir::ZeroAttr::get(getContext(), t);
}

mlir::TypedAttr getZeroInitAttr(mlir::Type ty) {
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We need to update this function in the incubator to add the missing types @andykaylor

if (mlir::isa<cir::IntType>(ty))
return cir::IntAttr::get(ty, 0);
if (cir::isAnyFloatingPointType(ty))
return cir::FPAttr::getZero(ty);
if (auto arrTy = mlir::dyn_cast<cir::ArrayType>(ty))
return getZeroAttr(arrTy);
if (auto ptrTy = mlir::dyn_cast<cir::PointerType>(ty))
return getConstNullPtrAttr(ptrTy);
if (mlir::isa<cir::BoolType>(ty)) {
return getCIRBoolAttr(false);
}
llvm_unreachable("Zero initializer for given type is NYI");
}

cir::ConstantOp getBool(bool state, mlir::Location loc) {
return create<cir::ConstantOp>(loc, getBoolTy(), getCIRBoolAttr(state));
}
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7 changes: 5 additions & 2 deletions clang/lib/CIR/CodeGen/CIRGenModule.cpp
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Expand Up @@ -140,17 +140,20 @@ void CIRGenModule::emitGlobalVarDefinition(const clang::VarDecl *vd,
// certain constant expressions is implemented for now.
const VarDecl *initDecl;
const Expr *initExpr = vd->getAnyInitializer(initDecl);
mlir::Attribute initializer;
if (initExpr) {
mlir::Attribute initializer;
if (APValue *value = initDecl->evaluateValue()) {
ConstantEmitter emitter(*this);
initializer = emitter.tryEmitPrivateForMemory(*value, astTy);
} else {
errorNYI(initExpr->getSourceRange(), "non-constant initializer");
}
varOp.setInitialValueAttr(initializer);
} else {
initializer = builder.getZeroInitAttr(convertType(astTy));
}

varOp.setInitialValueAttr(initializer);

// Set CIR's linkage type as appropriate.
cir::GlobalLinkageKind linkage =
getCIRLinkageVarDefinition(vd, /*IsConstant=*/false);
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8 changes: 4 additions & 4 deletions clang/test/CIR/CodeGen/array.cpp
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@@ -1,16 +1,16 @@
// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o - 2>&1 | FileCheck %s

int a[10];
// CHECK: cir.global external @a : !cir.array<!s32i x 10>
// CHECK: cir.global external @a = #cir.zero : !cir.array<!s32i x 10>

int aa[10][5];
// CHECK: cir.global external @aa : !cir.array<!cir.array<!s32i x 5> x 10>
// CHECK: cir.global external @aa = #cir.zero : !cir.array<!cir.array<!s32i x 5> x 10>

extern int b[10];
// CHECK: cir.global external @b : !cir.array<!s32i x 10>
// CHECK: cir.global external @b = #cir.zero : !cir.array<!s32i x 10>

extern int bb[10][5];
// CHECK: cir.global external @bb : !cir.array<!cir.array<!s32i x 5> x 10>
// CHECK: cir.global external @bb = #cir.zero : !cir.array<!cir.array<!s32i x 5> x 10>

int c[10] = {};
// CHECK: cir.global external @c = #cir.zero : !cir.array<!s32i x 10>
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8 changes: 4 additions & 4 deletions clang/test/CIR/Lowering/array.cpp
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@@ -1,16 +1,16 @@
// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - 2>&1 | FileCheck %s

int a[10];
// CHECK: @a = external dso_local global [10 x i32]
// CHECK: @a = dso_local global [10 x i32] zeroinitializer

int aa[10][5];
// CHECK: @aa = external dso_local global [10 x [5 x i32]]
// CHECK: @aa = dso_local global [10 x [5 x i32]] zeroinitializer

extern int b[10];
// CHECK: @b = external dso_local global [10 x i32]
// CHECK: @b = dso_local global [10 x i32] zeroinitializer

extern int bb[10][5];
// CHECK: @bb = external dso_local global [10 x [5 x i32]]
// CHECK: @bb = dso_local global [10 x [5 x i32]] zeroinitializer

int c[10] = {};
// CHECK: @c = dso_local global [10 x i32] zeroinitializer
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58 changes: 28 additions & 30 deletions clang/test/CIR/Lowering/global-var-simple.cpp
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@@ -1,21 +1,19 @@
// Global variables of intergal types
// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s
// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s

// Note: Currently unsupported features include default zero-initialization
// and alignment. The fact that "external" is only printed for globals
// without an initializer is a quirk of the LLVM AsmWriter.
// Note: Currently unsupported features include alignment..

char c;
// CHECK: @c = external dso_local global i8
// CHECK: @c = dso_local global i8 0

signed char sc;
// CHECK: @sc = external dso_local global i8
// CHECK: @sc = dso_local global i8 0

unsigned char uc;
// CHECK: @uc = external dso_local global i8
// CHECK: @uc = dso_local global i8 0

short ss;
// CHECK: @ss = external dso_local global i16
// CHECK: @ss = dso_local global i16 0

unsigned short us = 100;
// CHECK: @us = dso_local global i16 100
Expand All @@ -24,82 +22,82 @@ int si = 42;
// CHECK: @si = dso_local global i32 42

unsigned ui;
// CHECK: @ui = external dso_local global i32
// CHECK: @ui = dso_local global i32 0

long sl;
// CHECK: @sl = external dso_local global i64
// CHECK: @sl = dso_local global i64 0

unsigned long ul;
// CHECK: @ul = external dso_local global i64
// CHECK: @ul = dso_local global i64 0

long long sll;
// CHECK: @sll = external dso_local global i64
// CHECK: @sll = dso_local global i64 0

unsigned long long ull = 123456;
// CHECK: @ull = dso_local global i64 123456

__int128 s128;
// CHECK: @s128 = external dso_local global i128
// CHECK: @s128 = dso_local global i128 0

unsigned __int128 u128;
// CHECK: @u128 = external dso_local global i128
// CHECK: @u128 = dso_local global i128 0

wchar_t wc;
// CHECK: @wc = external dso_local global i32
// CHECK: @wc = dso_local global i32 0

char8_t c8;
// CHECK: @c8 = external dso_local global i8
// CHECK: @c8 = dso_local global i8 0

char16_t c16;
// CHECK: @c16 = external dso_local global i16
// CHECK: @c16 = dso_local global i16 0

char32_t c32;
// CHECK: @c32 = external dso_local global i32
// CHECK: @c32 = dso_local global i32 0

_BitInt(20) sb20;
// CHECK: @sb20 = external dso_local global i20
// CHECK: @sb20 = dso_local global i20 0

unsigned _BitInt(48) ub48;
// CHECK: @ub48 = external dso_local global i48
// CHECK: @ub48 = dso_local global i48 0

bool boolfalse = false;
// CHECK: @boolfalse = dso_local global i8 0

_Float16 f16;
// CHECK: @f16 = external dso_local global half
// CHECK: @f16 = dso_local global half

__bf16 bf16;
// CHECK: @bf16 = external dso_local global bfloat
// CHECK: @bf16 = dso_local global bfloat

float f;
// CHECK: @f = external dso_local global float
// CHECK: @f = dso_local global float 0.000000e+00

double d = 1.25;
// CHECK: @d = dso_local global double 1.250000e+00

long double ld;
// CHECK: @ld = external dso_local global x86_fp80
// CHECK: @ld = dso_local global x86_fp80 0xK00

__float128 f128;
// CHECK: @f128 = external dso_local global fp128
// CHECK: @f128 = dso_local global fp128 0xL00

void *vp;
// CHECK: @vp = external dso_local global ptr{{$}}
// CHECK: @vp = dso_local global ptr null

int *ip = 0;
// CHECK: @ip = dso_local global ptr null

double *dp;
// CHECK: @dp = external dso_local global ptr{{$}}
// CHECK: @dp = dso_local global ptr null

char **cpp;
// CHECK: @cpp = external dso_local global ptr{{$}}
// CHECK: @cpp = dso_local global ptr null

void (*fp)();
// CHECK: @fp = external dso_local global ptr{{$}}
// CHECK: @fp = dso_local global ptr null

int (*fpii)(int) = 0;
// CHECK: @fpii = dso_local global ptr null

void (*fpvar)(int, ...);
// CHECK: @fpvar = external dso_local global ptr{{$}}
// CHECK: @fpvar = dso_local global ptr null
2 changes: 1 addition & 1 deletion clang/test/CIR/Lowering/hello.c
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Expand Up @@ -3,7 +3,7 @@

int a;

// CHECK: @a = external dso_local global i32
// CHECK: @a = dso_local global i32 0

int b = 2;

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52 changes: 26 additions & 26 deletions clang/test/CIR/global-var-simple.cpp
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Expand Up @@ -2,16 +2,16 @@
// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o - | FileCheck %s

char c;
// CHECK: cir.global external @c : !s8i
// CHECK: cir.global external @c = #cir.int<0> : !s8i

signed char sc;
// CHECK: cir.global external @sc : !s8i
// CHECK: cir.global external @sc = #cir.int<0> : !s8i

unsigned char uc;
// CHECK: cir.global external @uc : !u8i
// CHECK: cir.global external @uc = #cir.int<0> : !u8i

short ss;
// CHECK: cir.global external @ss : !s16i
// CHECK: cir.global external @ss = #cir.int<0> : !s16i

unsigned short us = 100;
// CHECK: cir.global external @us = #cir.int<100> : !u16i
Expand All @@ -20,82 +20,82 @@ int si = 42;
// CHECK: cir.global external @si = #cir.int<42> : !s32i

unsigned ui;
// CHECK: cir.global external @ui : !u32i
// CHECK: cir.global external @ui = #cir.int<0> : !u32i

long sl;
// CHECK: cir.global external @sl : !s64i
// CHECK: cir.global external @sl = #cir.int<0> : !s64i

unsigned long ul;
// CHECK: cir.global external @ul : !u64i
// CHECK: cir.global external @ul = #cir.int<0> : !u64i

long long sll;
// CHECK: cir.global external @sll : !s64i
// CHECK: cir.global external @sll = #cir.int<0> : !s64i

unsigned long long ull = 123456;
// CHECK: cir.global external @ull = #cir.int<123456> : !u64i

__int128 s128;
// CHECK: cir.global external @s128 : !s128i
// CHECK: cir.global external @s128 = #cir.int<0> : !s128i

unsigned __int128 u128;
// CHECK: cir.global external @u128 : !u128i
// CHECK: cir.global external @u128 = #cir.int<0> : !u128i

wchar_t wc;
// CHECK: cir.global external @wc : !s32i
// CHECK: cir.global external @wc = #cir.int<0> : !s32i

char8_t c8;
// CHECK: cir.global external @c8 : !u8i
// CHECK: cir.global external @c8 = #cir.int<0> : !u8i

char16_t c16;
// CHECK: cir.global external @c16 : !u16i
// CHECK: cir.global external @c16 = #cir.int<0> : !u16i

char32_t c32;
// CHECK: cir.global external @c32 : !u32i
// CHECK: cir.global external @c32 = #cir.int<0> : !u32i

_BitInt(20) sb20;
// CHECK: cir.global external @sb20 : !cir.int<s, 20>
// CHECK: cir.global external @sb20 = #cir.int<0> : !cir.int<s, 20>

unsigned _BitInt(48) ub48;
// CHECK: cir.global external @ub48 : !cir.int<u, 48>
// CHECK: cir.global external @ub48 = #cir.int<0> : !cir.int<u, 48>

bool boolfalse = false;
// CHECK: cir.global external @boolfalse = #false

_Float16 f16;
// CHECK: cir.global external @f16 : !cir.f16
// CHECK: cir.global external @f16 = #cir.fp<0.000000e+00> : !cir.f16

__bf16 bf16;
// CHECK: cir.global external @bf16 : !cir.bf16
// CHECK: cir.global external @bf16 = #cir.fp<0.000000e+00> : !cir.bf16

float f;
// CHECK: cir.global external @f : !cir.float
// CHECK: cir.global external @f = #cir.fp<0.000000e+00> : !cir.float

double d = 1.25;
// CHECK: cir.global external @d = #cir.fp<1.250000e+00> : !cir.double

long double ld;
// CHECK: cir.global external @ld : !cir.long_double<!cir.f80>
// CHECK: cir.global external @ld = #cir.fp<0.000000e+00> : !cir.long_double<!cir.f80>

__float128 f128;
// CHECK: cir.global external @f128 : !cir.f128
// CHECK: cir.global external @f128 = #cir.fp<0.000000e+00> : !cir.f128

void *vp;
// CHECK: cir.global external @vp : !cir.ptr<!void>
// CHECK: cir.global external @vp = #cir.ptr<null> : !cir.ptr<!void>

int *ip = 0;
// CHECK: cir.global external @ip = #cir.ptr<null> : !cir.ptr<!s32i>

double *dp;
// CHECK: cir.global external @dp : !cir.ptr<!cir.double>
// CHECK: cir.global external @dp = #cir.ptr<null> : !cir.ptr<!cir.double>

char **cpp;
// CHECK: cir.global external @cpp : !cir.ptr<!cir.ptr<!s8i>>
// CHECK: cir.global external @cpp = #cir.ptr<null> : !cir.ptr<!cir.ptr<!s8i>>

void (*fp)();
// CHECK: cir.global external @fp : !cir.ptr<!cir.func<()>>
// CHECK: cir.global external @fp = #cir.ptr<null> : !cir.ptr<!cir.func<()>>

int (*fpii)(int) = 0;
// CHECK: cir.global external @fpii = #cir.ptr<null> : !cir.ptr<!cir.func<(!s32i) -> !s32i>>

void (*fpvar)(int, ...);
// CHECK: cir.global external @fpvar : !cir.ptr<!cir.func<(!s32i, ...)>>
// CHECK: cir.global external @fpvar = #cir.ptr<null> : !cir.ptr<!cir.func<(!s32i, ...)>>