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[CIR][CodeGen] Set constant properly for global variables (llvm#904)
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Fix llvm#801 (the remaining `constant` part). Actually the missing stage is
CIRGen.

There are two places where `GV.setConstant` is called:

* `buildGlobalVarDefinition`
* `getOrCreateCIRGlobal`

Therefore, the primary test `global-constant.c` contains a global
definition and a global declaration with use, which should be enough to
cover the two paths.

A test for OpenCL `constant` qualified global is also added. Some
existing testcases need tweaking to avoid failure of missing constant.
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@seven-mile @lanza
seven-mile authored and lanza committed Oct 2, 2024
1 parent d9c1133 commit c002332
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Showing 6 changed files with 41 additions and 22 deletions.
9 changes: 4 additions & 5 deletions clang/lib/CIR/CodeGen/CIRGenModule.cpp
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Expand Up @@ -947,9 +947,8 @@ CIRGenModule::getOrCreateCIRGlobal(StringRef MangledName, mlir::Type Ty,
// FIXME: This code is overly simple and should be merged with other global
// handling.
GV.setAlignmentAttr(getSize(astCtx.getDeclAlign(D)));
// TODO(cir):
// GV->setConstant(isTypeConstant(D->getType(), false));
// setLinkageForGV(GV, D);
GV.setConstant(isTypeConstant(D->getType(), false, false));
// TODO(cir): setLinkageForGV(GV, D);

if (D->getTLSKind()) {
if (D->getTLSKind() == VarDecl::TLS_Dynamic)
Expand Down Expand Up @@ -1278,8 +1277,8 @@ void CIRGenModule::buildGlobalVarDefinition(const clang::VarDecl *D,
emitter->finalize(GV);

// TODO(cir): If it is safe to mark the global 'constant', do so now.
// GV->setConstant(!NeedsGlobalCtor && !NeedsGlobalDtor &&
// isTypeConstant(D->getType(), true));
GV.setConstant(!NeedsGlobalCtor && !NeedsGlobalDtor &&
isTypeConstant(D->getType(), true, true));

// If it is in a read-only section, mark it 'constant'.
if (const SectionAttr *SA = D->getAttr<SectionAttr>())
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4 changes: 4 additions & 0 deletions clang/test/CIR/CodeGen/OpenCL/global.cl
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Expand Up @@ -11,6 +11,10 @@ global int b = 15;
// CIR-DAG: cir.global external addrspace(offload_global) @b = #cir.int<15> : !s32i
// LLVM-DAG: @b = addrspace(1) global i32 15

constant int c[2] = {18, 21};
// CIR-DAG: cir.global constant {{.*}}addrspace(offload_constant) {{.*}}@c
// LLVM-DAG: @c = addrspace(2) constant

kernel void test_get_global() {
a = b;
// CIR: %[[#ADDRB:]] = cir.get_global @b : !cir.ptr<!s32i, addrspace(offload_global)>
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28 changes: 14 additions & 14 deletions clang/test/CIR/CodeGen/cxx1z-inline-variables.cpp
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Expand Up @@ -26,13 +26,13 @@ const int &compat_use_after_redecl1 = compat::c;
const int &compat_use_after_redecl2 = compat::d;
const int &compat_use_after_redecl3 = compat::g;

// CIR: cir.global weak_odr comdat @_ZN6compat1bE = #cir.int<2> : !s32i {alignment = 4 : i64}
// CIR: cir.global weak_odr comdat @_ZN6compat1aE = #cir.int<1> : !s32i {alignment = 4 : i64}
// CIR: cir.global weak_odr comdat @_ZN6compat1cE = #cir.int<3> : !s32i {alignment = 4 : i64}
// CIR: cir.global external @_ZN6compat1eE = #cir.int<5> : !s32i {alignment = 4 : i64}
// CIR: cir.global weak_odr comdat @_ZN6compat1fE = #cir.int<6> : !s32i {alignment = 4 : i64}
// CIR: cir.global linkonce_odr comdat @_ZN6compat1dE = #cir.int<4> : !s32i {alignment = 4 : i64}
// CIR: cir.global linkonce_odr comdat @_ZN6compat1gE = #cir.int<7> : !s32i {alignment = 4 : i64}
// CIR: cir.global constant weak_odr comdat @_ZN6compat1bE = #cir.int<2> : !s32i {alignment = 4 : i64}
// CIR: cir.global constant weak_odr comdat @_ZN6compat1aE = #cir.int<1> : !s32i {alignment = 4 : i64}
// CIR: cir.global constant weak_odr comdat @_ZN6compat1cE = #cir.int<3> : !s32i {alignment = 4 : i64}
// CIR: cir.global constant external @_ZN6compat1eE = #cir.int<5> : !s32i {alignment = 4 : i64}
// CIR: cir.global constant weak_odr comdat @_ZN6compat1fE = #cir.int<6> : !s32i {alignment = 4 : i64}
// CIR: cir.global constant linkonce_odr comdat @_ZN6compat1dE = #cir.int<4> : !s32i {alignment = 4 : i64}
// CIR: cir.global constant linkonce_odr comdat @_ZN6compat1gE = #cir.int<7> : !s32i {alignment = 4 : i64}

// LLVM: $_ZN6compat1bE = comdat any
// LLVM: $_ZN6compat1aE = comdat any
Expand All @@ -41,10 +41,10 @@ const int &compat_use_after_redecl3 = compat::g;
// LLVM: $_ZN6compat1dE = comdat any
// LLVM: $_ZN6compat1gE = comdat any

// LLVM: @_ZN6compat1bE = weak_odr global i32 2, comdat, align 4
// LLVM: @_ZN6compat1aE = weak_odr global i32 1, comdat, align 4
// LLVM: @_ZN6compat1cE = weak_odr global i32 3, comdat, align 4
// LLVM: @_ZN6compat1eE = global i32 5, align 4
// LLVM: @_ZN6compat1fE = weak_odr global i32 6, comdat, align 4
// LLVM: @_ZN6compat1dE = linkonce_odr global i32 4, comdat, align 4
// LLVM: @_ZN6compat1gE = linkonce_odr global i32 7, comdat, align 4
// LLVM: @_ZN6compat1bE = weak_odr constant i32 2, comdat, align 4
// LLVM: @_ZN6compat1aE = weak_odr constant i32 1, comdat, align 4
// LLVM: @_ZN6compat1cE = weak_odr constant i32 3, comdat, align 4
// LLVM: @_ZN6compat1eE = constant i32 5, align 4
// LLVM: @_ZN6compat1fE = weak_odr constant i32 6, comdat, align 4
// LLVM: @_ZN6compat1dE = linkonce_odr constant i32 4, comdat, align 4
// LLVM: @_ZN6compat1gE = linkonce_odr constant i32 7, comdat, align 4
16 changes: 16 additions & 0 deletions clang/test/CIR/CodeGen/global-constant.c
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@@ -0,0 +1,16 @@
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o %t.ll
// RUN: FileCheck --check-prefix=LLVM --input-file=%t.ll %s

const int global_no_use = 12;
// CIR: cir.global constant {{.*}}@global_no_use
// LLVM: @global_no_use = constant

const float global_used = 1.2f;
// CIR: cir.global constant {{.*}}@global_used
// LLVM: @global_used = constant

float const * get_float_ptr() {
return &global_used;
}
2 changes: 1 addition & 1 deletion clang/test/CIR/CodeGen/globals.c
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Expand Up @@ -93,7 +93,7 @@ struct Glob {
} glob;

double *const glob_ptr = &glob.b[1];
// CHECK: cir.global external @glob_ptr = #cir.global_view<@glob, [2 : i32, 1 : i32]> : !cir.ptr<!cir.double>
// CHECK: cir.global constant external @glob_ptr = #cir.global_view<@glob, [2 : i32, 1 : i32]> : !cir.ptr<!cir.double>

// TODO: test tentatives with internal linkage.

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4 changes: 2 additions & 2 deletions clang/test/CIR/CodeGen/temporaries.cpp
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Expand Up @@ -32,8 +32,8 @@ const unsigned int n = 1234;
const int &r = (const int&)n;

// CHECK: cir.global "private" constant internal @_ZGR1r_ = #cir.int<1234> : !s32i
// CHECK-NEXT: cir.global external @r = #cir.global_view<@_ZGR1r_> : !cir.ptr<!s32i> {alignment = 8 : i64}
// CHECK-NEXT: cir.global constant external @r = #cir.global_view<@_ZGR1r_> : !cir.ptr<!s32i> {alignment = 8 : i64}

// LLVM: @_ZGR1r_ = internal constant i32 1234, align 4
// LLVM-NEXT: @r = global ptr @_ZGR1r_, align 8
// LLVM-NEXT: @r = constant ptr @_ZGR1r_, align 8

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