Merging r361237:

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r361237 | maskray | 2019-05-21 03:41:25 -0700 (Tue, 21 May 2019) | 14 lines

[PPC64] Update LocalEntry from assigned symbols

On PowerPC64 ELFv2 ABI, functions may have 2 entry points: global and local.
The local entry point location of a function is stored in the st_other field of the symbol, as an offset relative to the global entry point.

In order to make symbol assignments (e.g. .equ/.set) work properly with this, PPCTargetELFStreamer already copies the local entry bits from the source symbol to the destination one, on emitAssignment(). The problem is that this copy is performed only at the assignment location, where the source symbol may not yet have processed the .localentry directive, that sets the local entry. This may cause the destination symbol to end up with wrong local entry information. Other symbol info is not affected by this because, in this case, the destination symbol value is actually a symbol reference.

This change keeps track of these assignments, and update all needed st_other fields when finish() is called.

Patch by Leandro Lupori!

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D56586
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_80@362671 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp b/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
index a1e4e07b25af4b527da7004d660c143209acc664..78609ef3d4e094d057758bad1e4ccee31ced1dd0 100644 (file)
--- a/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
+++ b/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
@@ -15,6 +15,7 @@
 #include "InstPrinter/PPCInstPrinter.h"
 #include "MCTargetDesc/PPCMCAsmInfo.h"
 #include "PPCTargetStreamer.h"
+#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/BinaryFormat/ELF.h"
@@ -182,16 +183,33 @@ public:
 
   void emitAssignment(MCSymbol *S, const MCExpr *Value) override {
     auto *Symbol = cast<MCSymbolELF>(S);
+
     // When encoding an assignment to set symbol A to symbol B, also copy
     // the st_other bits encoding the local entry point offset.
-    if (Value->getKind() != MCExpr::SymbolRef)
-      return;
-    const auto &RhsSym = cast<MCSymbolELF>(
-        static_cast<const MCSymbolRefExpr *>(Value)->getSymbol());
-    unsigned Other = Symbol->getOther();
+    if (copyLocalEntry(Symbol, Value))
+      UpdateOther.insert(Symbol);
+    else
+      UpdateOther.erase(Symbol);
+  }
+
+  void finish() override {
+    for (auto *Sym : UpdateOther)
+      copyLocalEntry(Sym, Sym->getVariableValue());
+  }
+
+private:
+  SmallPtrSet<MCSymbolELF *, 32> UpdateOther;
+
+  bool copyLocalEntry(MCSymbolELF *D, const MCExpr *S) {
+    auto *Ref = dyn_cast<const MCSymbolRefExpr>(S);
+    if (!Ref)
+      return false;
+    const auto &RhsSym = cast<MCSymbolELF>(Ref->getSymbol());
+    unsigned Other = D->getOther();
     Other &= ~ELF::STO_PPC64_LOCAL_MASK;
     Other |= RhsSym.getOther() & ELF::STO_PPC64_LOCAL_MASK;
-    Symbol->setOther(Other);
+    D->setOther(Other);
+    return true;
   }
 };
 

diff --git a/test/MC/PowerPC/ppc64-localentry-symver.s b/test/MC/PowerPC/ppc64-localentry-symbols.s
similarity index 58%
rename from test/MC/PowerPC/ppc64-localentry-symver.s
rename to test/MC/PowerPC/ppc64-localentry-symbols.s
index 4c7490646db03154021346f150dca862f09e2a24..f1d5c5d0ab1ac0e92def148cce66befce4d27bc2 100644 (file)
--- a/test/MC/PowerPC/ppc64-localentry-symver.s
+++ b/test/MC/PowerPC/ppc64-localentry-symbols.s
@@ -4,6 +4,11 @@
 # CHECK: 0000000000000000 gw    F .text  00000000 0x60 __impl_foo
 # CHECK: 0000000000000000 g     F .text  00000000 0x60 foo
 # CHECK: 0000000000000000 gw    F .text  00000000 0x60 foo@FBSD_1.1
+# CHECK: 0000000000000008 g     F .text  00000000 0x60 func
+# CHECK: 0000000000000008 gw    F .text  00000000 0x60 weak_func
+
+.text
+.abiversion 2
 
 .globl foo
 .type foo,@function
@@ -15,3 +20,15 @@ foo:
 .symver __impl_foo, foo@FBSD_1.1
 .weak   __impl_foo
 .set    __impl_foo, foo
+
+.globl  func
+# Mimick FreeBSD weak function/reference
+.weak   weak_func
+.equ    weak_func, func
+
+.p2align 2
+.type    func,@function
+func:
+  nop
+  nop
+  .localentry func, 8