[PATCH] D54907: [PPC64] Support toc-optimization for '@got' relocations

[Sean Fertile via Phabricator via llvm-commits]

sfertile created this revision.
sfertile added reviewers: syzaara, ruiu, MaskRay, rdhindsa.
Herald added subscribers: jsji, kbarton, arichardson, nemanjai, emaste.
Herald added a reviewer: espindola.

Extends the toc-optimizations to the '@got' relocations.


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D54907

Files:
  ELF/Arch/PPC64.cpp
  test/ELF/ppc64-got-off.s


Index: test/ELF/ppc64-got-off.s
===================================================================
--- test/ELF/ppc64-got-off.s
+++ test/ELF/ppc64-got-off.s
@@ -8,6 +8,14 @@
 # RUN: ld.lld -shared --no-toc-optimize %t.o -o %t
 # RUN: llvm-objdump -d %t | FileCheck %s
 
+# RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %s -o %t.o
+# RUN: ld.lld -shared %t.o -o %t
+# RUN: llvm-objdump -d %t | FileCheck --check-prefix=OPT %s
+
+# RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %s -o %t.o
+# RUN: ld.lld -shared %t.o -o %t
+# RUN: llvm-objdump -d %t | FileCheck --check-prefix=OPT %s
+
         .abiversion 2
         .section ".text"
 
@@ -38,6 +46,15 @@
 # CHECK-NEXT:    li  6, 0
 # CHECK-NEXT:    ori 6, 6, 32776
 
+# OPT-LABEL: func
+# OPT:         nop
+# OPT-NEXT:    ld 3, -32760(2)
+# OPT-NEXT:    ld 4, -32760(2)
+# OPT-NEXT:    lis 5, -1
+# OPT-NEXT:    ori 5, 5, 32776
+# OPT-NEXT:    li  6, 0
+# OPT-NEXT:    ori 6, 6, 32776
+
 # Since the got entry for a is .got[1] and the TOC base points to
 # .got + 0x8000, the offset for a at got is -0x7FF8 --> -32760
 
Index: ELF/Arch/PPC64.cpp
===================================================================
--- ELF/Arch/PPC64.cpp
+++ ELF/Arch/PPC64.cpp
@@ -596,15 +596,23 @@
   }
 }
 
-static bool isTocRelType(RelType Type) {
-  return Type == R_PPC64_TOC16_HA || Type == R_PPC64_TOC16_LO_DS ||
-         Type == R_PPC64_TOC16_LO;
+static bool isTocOptType(RelType Type) {
+  switch (Type) {
+  case R_PPC64_GOT16_HA:
+  case R_PPC64_GOT16_LO_DS:
+  case R_PPC64_TOC16_HA:
+  case R_PPC64_TOC16_LO_DS:
+  case R_PPC64_TOC16_LO:
+    return true;
+  default:
+    return false;
+  }
 }
 
 void PPC64::relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const {
   // We need to save the original relocation type to determine if we should
   // toc-optimize the instructions being relocated.
-  bool IsTocRelType = isTocRelType(Type);
+  bool ShouldTocOptimize =  isTocOptType(Type);
   // For TOC-relative and GOT-indirect relocations, proceed in terms of the
   // corresponding ADDR16 relocation type.
   std::tie(Type, Val) = toAddr16Rel(Type, Val);
@@ -634,7 +642,7 @@
   case R_PPC64_ADDR16_HA:
   case R_PPC64_REL16_HA:
   case R_PPC64_TPREL16_HA:
-    if (Config->TocOptimize && IsTocRelType && ha(Val) == 0)
+    if (Config->TocOptimize && ShouldTocOptimize && ha(Val) == 0)
       writeInstrFromHalf16(Loc, 0x60000000);
     else
       write16(Loc, ha(Val));
@@ -666,7 +674,7 @@
     // When the high-adjusted part of a toc relocation evalutes to 0, it is
     // changed into a nop. The lo part then needs to be updated to use the
     // toc-pointer register r2, as the base register.
-    if (Config->TocOptimize && IsTocRelType && ha(Val) == 0) {
+    if (Config->TocOptimize && ShouldTocOptimize && ha(Val) == 0) {
       uint32_t Instr = readInstrFromHalf16(Loc);
       if (isInstructionUpdateForm(Instr))
         error(getErrorLocation(Loc) +
@@ -684,7 +692,7 @@
     uint32_t Inst = readInstrFromHalf16(Loc);
     uint16_t Mask = isDQFormInstruction(Inst) ? 0xF : 0x3;
     checkAlignment(Loc, lo(Val), Mask + 1, Type);
-    if (Config->TocOptimize && IsTocRelType && ha(Val) == 0) {
+    if (Config->TocOptimize && ShouldTocOptimize && ha(Val) == 0) {
       // When the high-adjusted part of a toc relocation evalutes to 0, it is
       // changed into a nop. The lo part then needs to be updated to use the toc
       // pointer register r2, as the base register.


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