[ELF][PPC64] Actually implement --no-power10-stubs

When a caller that does not use TOC calls a function, a call stub is needed if
the function may use TOC. --no-power10-stubs avoids PC-relative instructions in
the code sequence.

The --no-power10-stubs=no implementation added in D94627 is wrong.
First, the first instruction incorrectly uses `mflr 0` (instead of `mflr 12`).
Second, for the PLT case, it uses addis+addi with getVA instead of addis+ld with
getGotPltVA.

2 files changed, 11 insertions, 11 deletions

diff --git a/lld/ELF/Thunks.cpp b/lld/ELF/Thunks.cpp
index ce35bb525835..ca0d34dce7dc 100644
--- a/lld/ELF/Thunks.cpp
+++ b/lld/ELF/Thunks.cpp
@@ -1089,13 +1089,17 @@ void PPC64R12SetupStub::writeTo(uint8_t *buf) {
         buf, (gotPlt ? PLD_R12_NO_DISP : PADDI_R12_NO_DISP) | imm);
     nextInstOffset = 8;
   } else {
-    uint32_t off = destination.getVA(addend) - getThunkTargetSym()->getVA() - 8;
-    write32(buf + 0, 0x7c0802a6);                      // mflr r12
-    write32(buf + 4, 0x429f0005);                      // bcl 20,31,.+4
-    write32(buf + 8, 0x7d6802a6);                      // mflr r11
-    write32(buf + 12, 0x7d8803a6);                     // mtlr r12
-    write32(buf + 16, 0x3d8b0000 | computeHiBits(off));// addis r12,r11,off@ha
-    write32(buf + 20, 0x398c0000 | (off & 0xffff));    // addi r12,r12,off@l
+    uint32_t off = offset - 8;
+    write32(buf + 0, 0x7d8802a6);                     // mflr 12
+    write32(buf + 4, 0x429f0005);                     // bcl 20,31,.+4
+    write32(buf + 8, 0x7d6802a6);                     // mflr 11
+    write32(buf + 12, 0x7d8803a6);                    // mtlr 12
+    write32(buf + 16,
+            0x3d8b0000 | ((off + 0x8000) >> 16));     // addis 12,11,off@ha
+    if (gotPlt)
+      write32(buf + 20, 0xe98c0000 | (off & 0xffff)); // ld 12, off@l(12)
+    else
+      write32(buf + 20, 0x398c0000 | (off & 0xffff)); // addi 12,12,off@l
     nextInstOffset = 24;
   }
   write32(buf + nextInstOffset, MTCTR_R12); // mtctr r12
diff --git a/lld/ELF/Thunks.h b/lld/ELF/Thunks.h
index 86aaee15f93b..12ddf08cadc0 100644
--- a/lld/ELF/Thunks.h
+++ b/lld/ELF/Thunks.h
@@ -73,10 +73,6 @@ void writePPC32PltCallStub(uint8_t *buf, uint64_t gotPltVA,
                            const InputFile *file, int64_t addend);
 void writePPC64LoadAndBranch(uint8_t *buf, int64_t offset);
 
-static inline uint16_t computeHiBits(uint32_t toCompute) {
-  return (toCompute + 0x8000) >> 16;
-}
-
 } // namespace lld::elf
 
 #endif