Subzero: Fix emission of global initializers.
Also changes the szbuild.py script to add -fdata-sections, and entirely removes the -disable-globals option.
The global initializer emission basically copies what llc does, based on 3 properties of the global: constant vs non-constant, internal vs external, and full zero-initializer vs non-trivial initializer.
BUG= none
R=jvoung@chromium.org, kschimpf@google.com
Review URL: https://codereview.chromium.org/631383003
diff --git a/src/IceTargetLoweringX8632.cpp b/src/IceTargetLoweringX8632.cpp
index 6829eee..343113c 100644
--- a/src/IceTargetLoweringX8632.cpp
+++ b/src/IceTargetLoweringX8632.cpp
@@ -4437,70 +4437,52 @@
return;
Ostream &Str = Ctx->getStrEmit();
- // constant:
- // .section .rodata,"a",@progbits
- // .align ALIGN
- // .byte ...
- // .size NAME, SIZE
-
- // non-constant:
- // .data
- // .align ALIGN
- // .byte ...
- // .size NAME, SIZE
-
- // zeroinitializer (constant):
- // (.section or .data as above)
- // .align ALIGN
- // .zero SIZE
- // .size NAME, SIZE
-
- // zeroinitializer (non-constant):
- // (.section or .data as above)
- // .local NAME
- // .comm NAME, SIZE, ALIGN
// TODO(kschimpf): Don't mangle name if external and uninitialized. This
// will allow us to cross test relocations for references to external
// global variables.
- IceString MangledName = Ctx->mangleName(Global.getName());
- // Start a new section.
- if (Ctx->getFlags().DataSections) {
- Str << "\t.section\t.rodata." << MangledName << ",\"a\",@progbits\n";
- } else if (Global.getIsConstant()) {
- Str << "\t.section\t.rodata,\"a\",@progbits\n";
- } else {
- Str << "\t.type\t" << MangledName << ",@object\n";
- Str << "\t.data\n";
- }
-
- Str << "\t" << (Global.getIsInternal() ? ".local" : ".global") << "\t"
- << MangledName << "\n";
-
const GlobalAddress::InitializerListType &Initializers =
Global.getInitializers();
+ assert(Initializers.size());
+ bool HasInitializer =
+ !(Initializers.size() == 1 &&
+ llvm::isa<GlobalAddress::ZeroInitializer>(Initializers[0]));
+ bool IsConstant = Global.getIsConstant();
+ bool IsExternal = !Global.getIsInternal();
+ uint32_t Align = Global.getAlignment();
+ SizeT Size = Global.getNumBytes();
+ IceString MangledName = Ctx->mangleName(Global.getName());
+ IceString SectionSuffix = "";
+ if (Ctx->getFlags().DataSections)
+ SectionSuffix = "." + MangledName;
- // Note: Handle zero initializations specially when lowering, since
- // we may be able to reduce object size.
- GlobalAddress::ZeroInitializer *SimpleZeroInit = nullptr;
- if (Initializers.size() == 1) {
- GlobalAddress::Initializer *Init = Initializers[0];
- if (const auto ZeroInit =
- llvm::dyn_cast<GlobalAddress::ZeroInitializer>(Init)) {
- SimpleZeroInit = ZeroInit;
- }
- }
+ Str << "\t.type\t" << MangledName << ",@object\n";
- if (SimpleZeroInit && !Global.getIsConstant()) {
- // TODO(stichnot): Put the appropriate non-constant
- // zeroinitializers in a .bss section to reduce object size.
- Str << "\t.comm\t" << MangledName << ", " << Global.getNumBytes() << ", "
- << Global.getAlignment() << "\n";
- // }
- } else {
- Str << "\t.align\t" << Global.getAlignment() << "\n";
+ if (IsConstant)
+ Str << "\t.section\t.rodata" << SectionSuffix << ",\"a\",@progbits\n";
+ else if (HasInitializer)
+ Str << "\t.section\t.data" << SectionSuffix << ",\"aw\",@progbits\n";
+ else if (IsExternal)
+ Str << "\t.section\t.bss" << SectionSuffix << ",\"aw\",@nobits\n";
+ // No .section for non-constant + zeroinitializer + internal
+
+ if (IsExternal)
+ Str << "\t.globl\t" << MangledName << "\n";
+ else if (!IsConstant && !HasInitializer)
+ Str << "\t.local\t" << MangledName << "\n";
+ // Internal symbols only get .local when using .comm.
+
+ if ((IsConstant || HasInitializer || IsExternal) && Align > 1)
+ Str << "\t.align\t" << Align << "\n";
+ // Alignment is part of .comm.
+
+ if (IsConstant || HasInitializer || IsExternal)
Str << MangledName << ":\n";
+ else
+ Str << "\t.comm\t" << MangledName << "," << Size << "," << Align << "\n";
+
+ if (HasInitializer) {
for (GlobalAddress::Initializer *Init : Initializers) {
switch (Init->getKind()) {
case GlobalAddress::Initializer::DataInitializerKind: {
@@ -4539,8 +4521,13 @@
}
}
}
- Str << "\t.size\t" << MangledName << ", " << Global.getNumBytes() << "\n";
- }
+ } else if (IsConstant || IsExternal)
+ Str << "\t.zero\t" << Size << "\n";
+ // Size is part of .comm.
+
+ if (IsConstant || HasInitializer || IsExternal)
+ Str << "\t.size\t" << MangledName << ", " << Size << "\n";
+ // Size is part of .comm.
}
} // end of namespace Ice
