RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-11-22 18:54:02 +01:00
Code Issues Projects Releases Wiki Activity

[PowerPC] Fix large code model with the ELFv2 ABI

Browse Source 
The global entry point prologue currently assumes that the TOC
associated with a function is less than 2GB away from the function
entry point.  This is always true when using the medium or small
code model, but may not be the case when using the large code model.

This patch adds a new variant of the ELFv2 global entry point prologue
that lifts the 2GB restriction when building with -mcmodel=large.
This works by emitting a quadword containing the distance from the
function entry point to its associated TOC immediately before the
entry point, and then using a prologue like:

ld r2,-8(r12)
add r2,r2,r12

Since creation of the entry point prologue is now split across two
separate routines (PPCLinuxAsmPrinter::EmitFunctionEntryLabel emits
the data word, PPCLinuxAsmPrinter::EmitFunctionBodyStart the prolog
code), I've switched to using named labels instead of just temporaries
to indicate the locations of the global and local entry points and the
new TOC offset data word.

These names are provided by new routines in PPCFunctionInfo modeled
after the existing PPCFunctionInfo::getPICOffsetSymbol.

Note that a corresponding change was committed to GCC here:
https://gcc.gnu.org/ml/gcc-patches/2015-12/msg00355.html

Reviewers: hfinkel

Differential Revision: http://reviews.llvm.org/D15500

llvm-svn: 257597
This commit is contained in:
Ulrich Weigand 2016-01-13 13:12:23 +00:00
parent 3e4a1e477a
commit 257810adf2
5 changed files with 136 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

96
lib/Target/PowerPC/PPCAsmPrinter.cpp
View File

@ -1092,8 +1092,28 @@ void PPCLinuxAsmPrinter::EmitFunctionEntryLabel() {
}
// ELFv2 ABI - Normal entry label.
if (Subtarget->isELFv2ABI())
if (Subtarget->isELFv2ABI()) {
// In the Large code model, we allow arbitrary displacements between
// the text section and its associated TOC section. We place the
// full 8-byte offset to the TOC in memory immediatedly preceding
// the function global entry point.
if (TM.getCodeModel() == CodeModel::Large
&& !MF->getRegInfo().use_empty(PPC::X2)) {
const PPCFunctionInfo *PPCFI = MF->getInfo<PPCFunctionInfo>();
MCSymbol *TOCSymbol = OutContext.getOrCreateSymbol(StringRef(".TOC."));
MCSymbol *GlobalEPSymbol = PPCFI->getGlobalEPSymbol();
const MCExpr *TOCDeltaExpr =
MCBinaryExpr::createSub(MCSymbolRefExpr::create(TOCSymbol, OutContext),
MCSymbolRefExpr::create(GlobalEPSymbol,
OutContext),
OutContext);
OutStreamer->EmitLabel(PPCFI->getTOCOffsetSymbol());
OutStreamer->EmitValue(TOCDeltaExpr, 8);
}
return AsmPrinter::EmitFunctionEntryLabel();
}
// Emit an official procedure descriptor.
MCSectionSubPair Current = OutStreamer->getCurrentSection();
@ -1160,10 +1180,25 @@ void PPCLinuxAsmPrinter::EmitFunctionBodyStart() {
// thus emit a prefix sequence along the following lines:
//
// func:
// .Lfunc_gepNN:
// # global entry point
// addis r2,r12,(.TOC.-func)@ha
// addi r2,r2,(.TOC.-func)@l
// .localentry func, .-func
// addis r2,r12,(.TOC.-.Lfunc_gepNN)@ha
// addi r2,r2,(.TOC.-.Lfunc_gepNN)@l
// .Lfunc_lepNN:
// .localentry func, .Lfunc_lepNN-.Lfunc_gepNN
// # local entry point, followed by function body
//
// For the Large code model, we create
//
// .Lfunc_tocNN:
// .quad .TOC.-.Lfunc_gepNN # done by EmitFunctionEntryLabel
// func:
// .Lfunc_gepNN:
// # global entry point
// ld r2,.Lfunc_tocNN-.Lfunc_gepNN(r12)
// add r2,r2,r12
// .Lfunc_lepNN:
// .localentry func, .Lfunc_lepNN-.Lfunc_gepNN
// # local entry point, followed by function body
//
// This ensures we have r2 set up correctly while executing the function
@ -1171,32 +1206,49 @@ void PPCLinuxAsmPrinter::EmitFunctionBodyStart() {
if (Subtarget->isELFv2ABI()
// Only do all that if the function uses r2 in the first place.
&& !MF->getRegInfo().use_empty(PPC::X2)) {
const PPCFunctionInfo *PPCFI = MF->getInfo<PPCFunctionInfo>();
MCSymbol *GlobalEntryLabel = OutContext.createTempSymbol();
MCSymbol *GlobalEntryLabel = PPCFI->getGlobalEPSymbol();
OutStreamer->EmitLabel(GlobalEntryLabel);
const MCSymbolRefExpr *GlobalEntryLabelExp =
MCSymbolRefExpr::create(GlobalEntryLabel, OutContext);
MCSymbol *TOCSymbol = OutContext.getOrCreateSymbol(StringRef(".TOC."));
const MCExpr *TOCDeltaExpr =
MCBinaryExpr::createSub(MCSymbolRefExpr::create(TOCSymbol, OutContext),
GlobalEntryLabelExp, OutContext);
if (TM.getCodeModel() != CodeModel::Large) {
MCSymbol *TOCSymbol = OutContext.getOrCreateSymbol(StringRef(".TOC."));
const MCExpr *TOCDeltaExpr =
MCBinaryExpr::createSub(MCSymbolRefExpr::create(TOCSymbol, OutContext),
GlobalEntryLabelExp, OutContext);
const MCExpr *TOCDeltaHi =
PPCMCExpr::createHa(TOCDeltaExpr, false, OutContext);
EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDIS)
.addReg(PPC::X2)
.addReg(PPC::X12)
.addExpr(TOCDeltaHi));
const MCExpr *TOCDeltaHi =
PPCMCExpr::createHa(TOCDeltaExpr, false, OutContext);
EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDIS)
.addReg(PPC::X2)
.addReg(PPC::X12)
.addExpr(TOCDeltaHi));
const MCExpr *TOCDeltaLo =
PPCMCExpr::createLo(TOCDeltaExpr, false, OutContext);
EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDI)
.addReg(PPC::X2)
.addReg(PPC::X2)
.addExpr(TOCDeltaLo));
const MCExpr *TOCDeltaLo =
PPCMCExpr::createLo(TOCDeltaExpr, false, OutContext);
EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDI)
.addReg(PPC::X2)
.addReg(PPC::X2)
.addExpr(TOCDeltaLo));
} else {
MCSymbol *TOCOffset = PPCFI->getTOCOffsetSymbol();
const MCExpr *TOCOffsetDeltaExpr =
MCBinaryExpr::createSub(MCSymbolRefExpr::create(TOCOffset, OutContext),
GlobalEntryLabelExp, OutContext);
MCSymbol *LocalEntryLabel = OutContext.createTempSymbol();
EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::LD)
.addReg(PPC::X2)
.addExpr(TOCOffsetDeltaExpr)
.addReg(PPC::X12));
EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADD8)
.addReg(PPC::X2)
.addReg(PPC::X2)
.addReg(PPC::X12));
}
MCSymbol *LocalEntryLabel = PPCFI->getLocalEPSymbol();
OutStreamer->EmitLabel(LocalEntryLabel);
const MCSymbolRefExpr *LocalEntryLabelExp =
MCSymbolRefExpr::create(LocalEntryLabel, OutContext);

21
lib/Target/PowerPC/PPCMachineFunctionInfo.cpp
View File

@ -23,3 +23,24 @@ MCSymbol *PPCFunctionInfo::getPICOffsetSymbol() const {
Twine(MF.getFunctionNumber()) +
"$poff");
}
MCSymbol *PPCFunctionInfo::getGlobalEPSymbol() const {
const DataLayout &DL = MF.getDataLayout();
return MF.getContext().getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
"func_gep" +
Twine(MF.getFunctionNumber()));
}
MCSymbol *PPCFunctionInfo::getLocalEPSymbol() const {
const DataLayout &DL = MF.getDataLayout();
return MF.getContext().getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
"func_lep" +
Twine(MF.getFunctionNumber()));
}
MCSymbol *PPCFunctionInfo::getTOCOffsetSymbol() const {
const DataLayout &DL = MF.getDataLayout();
return MF.getContext().getOrCreateSymbol(Twine(DL.getPrivateGlobalPrefix()) +
"func_toc" +
Twine(MF.getFunctionNumber()));
}

4
lib/Target/PowerPC/PPCMachineFunctionInfo.h
View File

@ -197,6 +197,10 @@ public:
bool usesPICBase() const { return UsesPICBase; }
MCSymbol *getPICOffsetSymbol() const;
MCSymbol *getGlobalEPSymbol() const;
MCSymbol *getLocalEPSymbol() const;
MCSymbol *getTOCOffsetSymbol() const;
};
} // end of namespace llvm

27
test/CodeGen/PowerPC/ppc64le-localentry-large.ll Normal file
View File

@ -0,0 +1,27 @@
; RUN: llc -march=ppc64le -code-model=large < %s | FileCheck %s
target datalayout = "e-m:e-i64:64-n32:64"
target triple = "powerpc64le-unknown-linux-gnu"
@number64 = global i64 10, align 8
; CHECK: .abiversion 2
define i64 @use_toc(i64 %a) nounwind {
entry:
; CHECK: .Lfunc_toc[[FN:[0-9]+]]:
; CHECK-NEXT: .quad .TOC.-.Lfunc_gep[[FN]]
; CHECK: use_toc:
; CHECK-NEXT: .L{{.*}}:
; CHECK-NEXT: .Lfunc_gep[[FN]]:
; CHECK-NEXT: ld 2, .Lfunc_toc[[FN]]-.Lfunc_gep[[FN]](12)
; CHECK-NEXT: add 2, 2, 12
; CHECK-NEXT: .Lfunc_lep[[FN]]:
; CHECK-NEXT: .localentry use_toc, .Lfunc_lep[[FN]]-.Lfunc_gep[[FN]]
; CHECK-NEXT: %entry
%0 = load i64, i64* @number64, align 8
%cmp = icmp eq i64 %0, %a
%conv1 = zext i1 %cmp to i64
ret i64 %conv1
}

20
test/CodeGen/PowerPC/ppc64le-localentry.ll
View File

@ -17,11 +17,11 @@ define i64 @use_toc(i64 %a) nounwind {
entry:
; CHECK-LABEL: @use_toc
; CHECK-NEXT: .L{{.*}}:
; CHECK-NEXT: .Ltmp[[TMP1:[0-9]+]]:
; CHECK-NEXT: addis 2, 12, .TOC.-.Ltmp[[TMP1]]@ha
; CHECK-NEXT: addi 2, 2, .TOC.-.Ltmp[[TMP1]]@l
; CHECK-NEXT: .Ltmp[[TMP2:[0-9]+]]:
; CHECK-NEXT: .localentry use_toc, .Ltmp[[TMP2]]-.Ltmp[[TMP1]]
; CHECK-NEXT: .Lfunc_gep[[FN:[0-9]+]]:
; CHECK-NEXT: addis 2, 12, .TOC.-.Lfunc_gep[[FN]]@ha
; CHECK-NEXT: addi 2, 2, .TOC.-.Lfunc_gep[[FN]]@l
; CHECK-NEXT: .Lfunc_lep[[FN]]:
; CHECK-NEXT: .localentry use_toc, .Lfunc_lep[[FN]]-.Lfunc_gep[[FN]]
; CHECK-NEXT: %entry
%0 = load i64, i64* @number64, align 8
%cmp = icmp eq i64 %0, %a
@ -34,11 +34,11 @@ define void @use_toc_implicit() nounwind {
entry:
; CHECK-LABEL: @use_toc_implicit
; CHECK-NEXT: .L{{.*}}:
; CHECK-NEXT: .Ltmp[[TMP1:[0-9]+]]:
; CHECK-NEXT: addis 2, 12, .TOC.-.Ltmp[[TMP1]]@ha
; CHECK-NEXT: addi 2, 2, .TOC.-.Ltmp[[TMP1]]@l
; CHECK-NEXT: .Ltmp[[TMP2:[0-9]+]]:
; CHECK-NEXT: .localentry use_toc_implicit, .Ltmp[[TMP2]]-.Ltmp[[TMP1]]
; CHECK-NEXT: .Lfunc_gep[[FN:[0-9]+]]:
; CHECK-NEXT: addis 2, 12, .TOC.-.Lfunc_gep[[FN]]@ha
; CHECK-NEXT: addi 2, 2, .TOC.-.Lfunc_gep[[FN]]@l
; CHECK-NEXT: .Lfunc_lep[[FN]]:
; CHECK-NEXT: .localentry use_toc_implicit, .Lfunc_lep[[FN]]-.Lfunc_gep[[FN]]
; CHECK-NEXT: %entry
call void @callee()
ret void