[llvm] [AIX] [XCOFF] Add support for common and local common symbols in the TOC (PR #79530)
Zaara Syeda via llvm-commits
llvm-commits at lists.llvm.org
Thu Jan 25 16:38:16 PST 2024
https://github.com/syzaara created https://github.com/llvm/llvm-project/pull/79530
This patch adds support for common and local symbols in the TOC for AIX. Note that we need to update isVirtualSection so as a common symbol in TOC will have the symbol type XTY_CM and will be initialized when placed in the TOC so sections with this type are no longer virtual.
>From 15471a2bf6c17ce2197ba7ebf20668b6c7b220ad Mon Sep 17 00:00:00 2001
From: Zaara Syeda <syzaara at cpap8104.rtp.raleigh.ibm.com>
Date: Thu, 25 Jan 2024 19:32:41 -0500
Subject: [PATCH] [AIX] [XCOFF] Add support for common and local common symbols
in the TOC
This patch adds support for common and local symbols in the TOC for AIX.
Note that we need to update isVirtualSection so as a common symbol in TOC will
have the symbol type XTY_CM and will be initialized when placed in the TOC so
sections with this type are no longer virtual.
---
llvm/lib/MC/MCSectionXCOFF.cpp | 9 +++++++-
llvm/lib/MC/XCOFFObjectWriter.cpp | 10 ++++++--
llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp | 23 +++++++++++++++----
llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp | 7 ++----
.../PowerPC/basic-toc-data-local-linkage.ll | 10 ++++----
5 files changed, 43 insertions(+), 16 deletions(-)
diff --git a/llvm/lib/MC/MCSectionXCOFF.cpp b/llvm/lib/MC/MCSectionXCOFF.cpp
index 02b1b972f339bf..95d32e3580e3f5 100644
--- a/llvm/lib/MC/MCSectionXCOFF.cpp
+++ b/llvm/lib/MC/MCSectionXCOFF.cpp
@@ -82,6 +82,11 @@ void MCSectionXCOFF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
}
if (isCsect() && getMappingClass() == XCOFF::XMC_TD) {
+ // Common csect type (uninitialized storage) does not have to print csect
+ // directive for section switching unless it is local.
+ if (getKind().isCommon() && !getKind().isBSSLocal())
+ return;
+
assert((getKind().isBSSExtern() || getKind().isBSSLocal()) &&
"Unexepected section kind for toc-data");
printCsectDirective(OS);
@@ -135,5 +140,7 @@ bool MCSectionXCOFF::isVirtualSection() const {
return false;
assert(isCsect() &&
"Handling for isVirtualSection not implemented for this section!");
- return XCOFF::XTY_CM == CsectProp->Type;
+ // XTY_CM sections are virtual except for toc-data symbols.
+ return (XCOFF::XTY_CM == CsectProp->Type) &&
+ (getMappingClass() != XCOFF::XMC_TD);
}
diff --git a/llvm/lib/MC/XCOFFObjectWriter.cpp b/llvm/lib/MC/XCOFFObjectWriter.cpp
index 343e2fc877bc3b..11f8a72edeadaf 100644
--- a/llvm/lib/MC/XCOFFObjectWriter.cpp
+++ b/llvm/lib/MC/XCOFFObjectWriter.cpp
@@ -533,9 +533,15 @@ CsectGroup &XCOFFObjectWriter::getCsectGroup(const MCSectionXCOFF *MCSec) {
return TOCCsects;
case XCOFF::XMC_TC:
case XCOFF::XMC_TE:
- case XCOFF::XMC_TD:
assert(XCOFF::XTY_SD == MCSec->getCSectType() &&
- "Only an initialized csect can contain TC entry.");
+ "A TOC symbol must be an initialized csect.");
+ assert(!TOCCsects.empty() &&
+ "We should at least have a TOC-base in this CsectGroup.");
+ return TOCCsects;
+ case XCOFF::XMC_TD:
+ assert((XCOFF::XTY_SD == MCSec->getCSectType() ||
+ XCOFF::XTY_CM == MCSec->getCSectType()) &&
+ "Symbol type incompatible with toc-data.");
assert(!TOCCsects.empty() &&
"We should at least have a TOC-base in this CsectGroup.");
return TOCCsects;
diff --git a/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp b/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
index 4f15ba497d84c4..1f4476d3907cdd 100644
--- a/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -2572,12 +2572,18 @@ void PPCAIXAsmPrinter::emitGlobalVariableHelper(const GlobalVariable *GV) {
GVSym->setStorageClass(
TargetLoweringObjectFileXCOFF::getStorageClassForGlobal(GV));
- if (GVKind.isBSSLocal() || GVKind.isThreadBSSLocal())
+ if (GVKind.isBSSLocal() && Csect->getMappingClass() == XCOFF::XMC_TD) {
+ OutStreamer->emitZeros(Size);
+ } else if (GVKind.isBSSLocal() || GVKind.isThreadBSSLocal()) {
+ assert(Csect->getMappingClass() != XCOFF::XMC_TD &&
+ "BSS local toc-data already handled and TLS variables "
+ "incompatible with XMC_TD");
OutStreamer->emitXCOFFLocalCommonSymbol(
OutContext.getOrCreateSymbol(GVSym->getSymbolTableName()), Size,
GVSym, Alignment);
- else
+ } else {
OutStreamer->emitCommonSymbol(GVSym, Size, Alignment);
+ }
return;
}
@@ -2738,8 +2744,17 @@ void PPCAIXAsmPrinter::emitEndOfAsmFile(Module &M) {
TS->emitTCEntry(*I.first.first, I.first.second);
}
- for (const auto *GV : TOCDataGlobalVars)
- emitGlobalVariableHelper(GV);
+ // Traverse the list of global variables twice, emitting all of the
+ // non-common global variables before the common ones, as emitting a
+ // .comm directive changes the scope from .toc to the common symbol.
+ for (const auto *GV : TOCDataGlobalVars) {
+ if (!GV->hasCommonLinkage())
+ emitGlobalVariableHelper(GV);
+ }
+ for (const auto *GV : TOCDataGlobalVars) {
+ if (GV->hasCommonLinkage())
+ emitGlobalVariableHelper(GV);
+ }
}
bool PPCAIXAsmPrinter::doInitialization(Module &M) {
diff --git a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index b57d185bb638b8..b86c9abeecf35f 100644
--- a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -551,13 +551,10 @@ static bool hasTocDataAttr(SDValue Val, unsigned PointerSize) {
"A GlobalVariable with size larger than a TOC entry is not currently "
"supported by the toc data transformation.");
- if (GV->hasLocalLinkage() || GV->hasPrivateLinkage())
- report_fatal_error("A GlobalVariable with private or local linkage is not "
+ if (GV->hasPrivateLinkage())
+ report_fatal_error("A GlobalVariable with private linkage is not "
"currently supported by the toc data transformation.");
- assert(!GV->hasCommonLinkage() &&
- "Tentative definitions cannot have the mapping class XMC_TD.");
-
return true;
}
diff --git a/llvm/test/CodeGen/PowerPC/basic-toc-data-local-linkage.ll b/llvm/test/CodeGen/PowerPC/basic-toc-data-local-linkage.ll
index 0e131672b421e4..4352852533ffb3 100644
--- a/llvm/test/CodeGen/PowerPC/basic-toc-data-local-linkage.ll
+++ b/llvm/test/CodeGen/PowerPC/basic-toc-data-local-linkage.ll
@@ -1,6 +1,6 @@
-; RUN: not --crash llc -mtriple powerpc-ibm-aix-xcoff -verify-machineinstrs \
+; RUN: llc -mtriple powerpc-ibm-aix-xcoff -verify-machineinstrs \
; RUN: < %s 2>&1 | FileCheck %s
-; RUN: not --crash llc -mtriple powerpc64-ibm-aix-xcoff -verify-machineinstrs \
+; RUN: llc -mtriple powerpc64-ibm-aix-xcoff -verify-machineinstrs \
; RUN: < %s 2>&1 | FileCheck %s
@ilocal = internal global i32 0, align 4 #0
@@ -11,6 +11,8 @@ define dso_local i32 @read_i32_local_linkage() {
ret i32 %0
}
-; CHECK: LLVM ERROR: A GlobalVariable with private or local linkage is not currently supported by the toc data transformation.
-
attributes #0 = { "toc-data" }
+
+; CHECK: .toc
+; CHECK-NEXT: .csect ilocal[TD],2
+; CHECK-NEXT: .space 4
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