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[PowerPC] Revert r185476 and fix up TLS variant kinds

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In the commit message to r185476 I wrote:

>The PowerPC-specific modifiers VK_PPC_TLSGD and VK_PPC_TLSLD
>correspond exactly to the generic modifiers VK_TLSGD and VK_TLSLD.
>This causes some confusion with the asm parser, since VK_PPC_TLSGD
>is output as @tlsgd, which is then read back in as VK_TLSGD.
>
>To avoid this confusion, this patch removes the PowerPC-specific
>modifiers and uses the generic modifiers throughout.  (The only
>drawback is that the generic modifiers are printed in upper case
>while the usual convention on PowerPC is to use lower-case modifiers.
>But this is just a cosmetic issue.)

This was unfortunately incorrect, there is is fact another,
serious drawback to using the default VK_TLSLD/VK_TLSGD
variant kinds: using these causes ELFObjectWriter::RelocNeedsGOT
to return true, which in turn causes the ELFObjectWriter to emit
an undefined reference to _GLOBAL_OFFSET_TABLE_.

This is a problem on powerpc64, because it uses the TOC instead
of the GOT, and the linker does not provide _GLOBAL_OFFSET_TABLE_,
so the symbol remains undefined.  This means shared libraries
using TLS built with the integrated assembler are currently
broken.

While the whole RelocNeedsGOT / _GLOBAL_OFFSET_TABLE_ situation
probably ought to be properly fixed at some point, for now I'm
simply reverting the r185476 commit.  Now this in turn exposes
the breakage of handling @tlsgd/@tlsld in the asm parser that
this check-in was originally intended to fix.

To avoid this regression, I'm also adding a different fix for
this problem: while common code now parses @tlsgd as VK_TLSGD,
a special hack in the asm parser translates this code to the
platform-specific VK_PPC_TLSGD that the back-end now expects.
While this is not really pretty, it's self-contained and
shouldn't hurt anything else for now.  One the underlying
problem is fixed, this hack can be reverted again.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185945 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ulrich Weigand 2013-07-09 16:41:09 +00:00
parent f2cfef8172
commit 7a34599db0
10 changed files with 73 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/llvm/MC/MCExpr.h
View File

@ -216,10 +216,12 @@ public:
VK_PPC_GOT_TLSGD_LO, // symbol@got@tlsgd@l
VK_PPC_GOT_TLSGD_HI, // symbol@got@tlsgd@h
VK_PPC_GOT_TLSGD_HA, // symbol@got@tlsgd@ha
VK_PPC_TLSGD, // symbol@tlsgd
VK_PPC_GOT_TLSLD, // symbol@got@tlsld
VK_PPC_GOT_TLSLD_LO, // symbol@got@tlsld@l
VK_PPC_GOT_TLSLD_HI, // symbol@got@tlsld@h
VK_PPC_GOT_TLSLD_HA, // symbol@got@tlsld@ha
VK_PPC_TLSLD, // symbol@tlsld
VK_Mips_GPREL,
VK_Mips_GOT_CALL,

2
lib/MC/MCELFStreamer.cpp
View File

@ -392,10 +392,12 @@ void MCELFStreamer::fixSymbolsInTLSFixups(const MCExpr *expr) {
case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_LO:
case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HI:
case MCSymbolRefExpr::VK_PPC_GOT_TLSGD_HA:
case MCSymbolRefExpr::VK_PPC_TLSGD:
case MCSymbolRefExpr::VK_PPC_GOT_TLSLD:
case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_LO:
case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HI:
case MCSymbolRefExpr::VK_PPC_GOT_TLSLD_HA:
case MCSymbolRefExpr::VK_PPC_TLSLD:
break;
}
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(symRef.getSymbol());

2
lib/MC/MCExpr.cpp
View File

@ -241,10 +241,12 @@ StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
case VK_PPC_GOT_TLSGD_LO: return "got@tlsgd@l";
case VK_PPC_GOT_TLSGD_HI: return "got@tlsgd@h";
case VK_PPC_GOT_TLSGD_HA: return "got@tlsgd@ha";
case VK_PPC_TLSGD: return "tlsgd";
case VK_PPC_GOT_TLSLD: return "got@tlsld";
case VK_PPC_GOT_TLSLD_LO: return "got@tlsld@l";
case VK_PPC_GOT_TLSLD_HI: return "got@tlsld@h";
case VK_PPC_GOT_TLSLD_HA: return "got@tlsld@ha";
case VK_PPC_TLSLD: return "tlsld";
case VK_Mips_GPREL: return "GPREL";
case VK_Mips_GOT_CALL: return "GOT_CALL";
case VK_Mips_GOT16: return "GOT16";

54
lib/Target/PowerPC/AsmParser/PPCAsmParser.cpp
View File

@ -190,6 +190,7 @@ class PPCAsmParser : public MCTargetAsmParser {
const MCExpr *ExtractModifierFromExpr(const MCExpr *E,
PPCMCExpr::VariantKind &Variant);
const MCExpr *FixupVariantKind(const MCExpr *E);
bool ParseExpression(const MCExpr *&EVal);
bool ParseOperand(SmallVectorImpl<MCParsedAsmOperand*> &Operands);
@ -1006,6 +1007,57 @@ ExtractModifierFromExpr(const MCExpr *E,
llvm_unreachable("Invalid expression kind!");
}
/// Find all VK_TLSGD/VK_TLSLD symbol references in expression and replace
/// them by VK_PPC_TLSGD/VK_PPC_TLSLD. This is necessary to avoid having
/// _GLOBAL_OFFSET_TABLE_ created via ELFObjectWriter::RelocNeedsGOT.
/// FIXME: This is a hack.
const MCExpr *PPCAsmParser::
FixupVariantKind(const MCExpr *E) {
MCContext &Context = getParser().getContext();
switch (E->getKind()) {
case MCExpr::Target:
case MCExpr::Constant:
return E;
case MCExpr::SymbolRef: {
const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(E);
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
switch (SRE->getKind()) {
case MCSymbolRefExpr::VK_TLSGD:
Variant = MCSymbolRefExpr::VK_PPC_TLSGD;
break;
case MCSymbolRefExpr::VK_TLSLD:
Variant = MCSymbolRefExpr::VK_PPC_TLSLD;
break;
default:
return E;
}
return MCSymbolRefExpr::Create(&SRE->getSymbol(), Variant, Context);
}
case MCExpr::Unary: {
const MCUnaryExpr *UE = cast<MCUnaryExpr>(E);
const MCExpr *Sub = FixupVariantKind(UE->getSubExpr());
if (Sub == UE->getSubExpr())
return E;
return MCUnaryExpr::Create(UE->getOpcode(), Sub, Context);
}
case MCExpr::Binary: {
const MCBinaryExpr *BE = cast<MCBinaryExpr>(E);
const MCExpr *LHS = FixupVariantKind(BE->getLHS());
const MCExpr *RHS = FixupVariantKind(BE->getRHS());
if (LHS == BE->getLHS() && RHS == BE->getRHS())
return E;
return MCBinaryExpr::Create(BE->getOpcode(), LHS, RHS, Context);
}
}
llvm_unreachable("Invalid expression kind!");
}
/// Parse an expression. This differs from the default "parseExpression"
/// in that it handles complex \code @l/@ha \endcode modifiers.
bool PPCAsmParser::
@ -1013,6 +1065,8 @@ ParseExpression(const MCExpr *&EVal) {
if (getParser().parseExpression(EVal))
return true;
EVal = FixupVariantKind(EVal);
PPCMCExpr::VariantKind Variant;
const MCExpr *E = ExtractModifierFromExpr(EVal, Variant);
if (E)

4
lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
View File

@ -312,10 +312,10 @@ unsigned PPCELFObjectWriter::getRelocTypeInner(const MCValue &Target,
case PPC::fixup_ppc_nofixup:
switch (Modifier) {
default: llvm_unreachable("Unsupported Modifier");
case MCSymbolRefExpr::VK_TLSGD:
case MCSymbolRefExpr::VK_PPC_TLSGD:
Type = ELF::R_PPC64_TLSGD;
break;
case MCSymbolRefExpr::VK_TLSLD:
case MCSymbolRefExpr::VK_PPC_TLSLD:
Type = ELF::R_PPC64_TLSLD;
break;
case MCSymbolRefExpr::VK_PPC_TLS:

6
lib/Target/PowerPC/PPCAsmPrinter.cpp
View File

@ -573,7 +573,8 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
const GlobalValue *GValue = MO.getGlobal();
MCSymbol *MOSymbol = Mang->getSymbol(GValue);
const MCExpr *SymVar =
MCSymbolRefExpr::Create(MOSymbol, MCSymbolRefExpr::VK_TLSGD, OutContext);
MCSymbolRefExpr::Create(MOSymbol, MCSymbolRefExpr::VK_PPC_TLSGD,
OutContext);
OutStreamer.EmitInstruction(MCInstBuilder(PPC::BL8_NOP_TLS)
.addExpr(TlsRef)
.addExpr(SymVar));
@ -624,7 +625,8 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
const GlobalValue *GValue = MO.getGlobal();
MCSymbol *MOSymbol = Mang->getSymbol(GValue);
const MCExpr *SymVar =
MCSymbolRefExpr::Create(MOSymbol, MCSymbolRefExpr::VK_TLSLD, OutContext);
MCSymbolRefExpr::Create(MOSymbol, MCSymbolRefExpr::VK_PPC_TLSLD,
OutContext);
OutStreamer.EmitInstruction(MCInstBuilder(PPC::BL8_NOP_TLS)
.addExpr(TlsRef)
.addExpr(SymVar));

2
test/CodeGen/PowerPC/tls-gd.ll
View File

@ -18,6 +18,6 @@ entry:
; CHECK: addis [[REG:[0-9]+]], 2, a@got@tlsgd@ha
; CHECK-NEXT: addi 3, [[REG]], a@got@tlsgd@l
; CHECK: bl __tls_get_addr(a@TLSGD)
; CHECK: bl __tls_get_addr(a@tlsgd)
; CHECK-NEXT: nop

2
test/CodeGen/PowerPC/tls-ld-2.ll
View File

@ -18,7 +18,7 @@ entry:
; CHECK: addis [[REG:[0-9]+]], 2, a@got@tlsld@ha
; CHECK-NEXT: addi 3, [[REG]], a@got@tlsld@l
; CHECK: bl __tls_get_addr(a@TLSLD)
; CHECK: bl __tls_get_addr(a@tlsld)
; CHECK-NEXT: nop
; CHECK: addis [[REG2:[0-9]+]], 3, a@dtprel@ha
; CHECK-NEXT: lwa {{[0-9]+}}, a@dtprel@l([[REG2]])

2
test/CodeGen/PowerPC/tls-ld.ll
View File

@ -18,7 +18,7 @@ entry:
; CHECK: addis [[REG:[0-9]+]], 2, a@got@tlsld@ha
; CHECK-NEXT: addi 3, [[REG]], a@got@tlsld@l
; CHECK: bl __tls_get_addr(a@TLSLD)
; CHECK: bl __tls_get_addr(a@tlsld)
; CHECK-NEXT: nop
; CHECK: addis [[REG2:[0-9]+]], 3, a@dtprel@ha
; CHECK-NEXT: addi {{[0-9]+}}, [[REG2]], a@dtprel@l

8
test/MC/PowerPC/ppc64-fixups.s
View File

@ -404,15 +404,15 @@ base:
# CHECK-REL: 0x{{[0-9A-F]*[26AE]}} R_PPC64_GOT_TLSLD16 target 0x0
addi 3, 3, target@got@tlsld
# CHECK: bl __tls_get_addr(target@TLSGD) # encoding: [0b010010BB,B,B,0bBBBBBB01]
# CHECK-NEXT: # fixup A - offset: 0, value: target@TLSGD, kind: fixup_ppc_nofixup
# CHECK: bl __tls_get_addr(target@tlsgd) # encoding: [0b010010BB,B,B,0bBBBBBB01]
# CHECK-NEXT: # fixup A - offset: 0, value: target@tlsgd, kind: fixup_ppc_nofixup
# CHECK-NEXT: # fixup B - offset: 0, value: __tls_get_addr, kind: fixup_ppc_br24
# CHECK-REL: 0x{{[0-9A-F]*[048C]}} R_PPC64_TLSGD target 0x0
# CHECK-REL-NEXT: 0x{{[0-9A-F]*[048C]}} R_PPC64_REL24 __tls_get_addr 0x0
bl __tls_get_addr(target@tlsgd)
# CHECK: bl __tls_get_addr(target@TLSLD) # encoding: [0b010010BB,B,B,0bBBBBBB01]
# CHECK-NEXT: # fixup A - offset: 0, value: target@TLSLD, kind: fixup_ppc_nofixup
# CHECK: bl __tls_get_addr(target@tlsld) # encoding: [0b010010BB,B,B,0bBBBBBB01]
# CHECK-NEXT: # fixup A - offset: 0, value: target@tlsld, kind: fixup_ppc_nofixup
# CHECK-NEXT: # fixup B - offset: 0, value: __tls_get_addr, kind: fixup_ppc_br24
# CHECK-REL: 0x{{[0-9A-F]*[048C]}} R_PPC64_TLSLD target 0x0
# CHECK-REL-NEXT: 0x{{[0-9A-F]*[048C]}} R_PPC64_REL24 __tls_get_addr 0x0