[PowerPC] Clean up generation of ha16() / lo16() markers

When targeting the Darwin assembler, we need to generate markers ha16() and
lo16() to designate the high and low parts of a (symbolic) immediate.  This
is necessary not just for plain symbols, but also for certain symbolic
expression, typically along the lines of ha16(A - B).  The latter doesn't
work when simply using VariantKind flags on the symbol reference.
This is why the current back-end uses hacks (explicitly called out as such
via multiple FIXMEs) in the symbolLo/symbolHi print methods.

This patch uses target-defined MCExpr codes to represent the Darwin
ha16/lo16 constructs, following along the lines of the equivalent solution
used by the ARM back end to handle their :upper16: / :lower16: markers.
This allows us to get rid of special handling both in the symbolLo/symbolHi
print method and in the common code MCExpr::print routine.  Instead, the
ha16 / lo16 markers are printed simply in a custom print routine for the
target MCExpr types.  (As a result, the symbolLo/symbolHi print methods
can now replaced by a single printS16ImmOperand routine that also handles
symbolic operands.)

The patch also provides a EvaluateAsRelocatableImpl routine to handle
ha16/lo16 constructs.  This is not actually used at the moment by any
in-tree code, but is provided as it makes merging into David Fang's
out-of-tree Mach-O object writer simpler.

Since there is no longer any need to treat VK_PPC_GAS_HA16 and
VK_PPC_DARWIN_HA16 differently, they are merged into a single
VK_PPC_ADDR16_HA (and likewise for the _LO16 types).

llvm-svn: 182616

1 files changed, 7 insertions, 18 deletions

diff --git a/llvm/lib/MC/MCExpr.cpp b/llvm/lib/MC/MCExpr.cpp
index 06bc72f2c6b..040b9289cf6 100644
--- a/llvm/lib/MC/MCExpr.cpp
+++ b/llvm/lib/MC/MCExpr.cpp
@@ -42,13 +42,6 @@ void MCExpr::print(raw_ostream &OS) const {
     // Parenthesize names that start with $ so that they don't look like
     // absolute names.
     bool UseParens = Sym.getName()[0] == '$';
-
-    if (SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_HA16 ||
-        SRE.getKind() == MCSymbolRefExpr::VK_PPC_DARWIN_LO16) {
-      OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
-      UseParens = true;
-    }
-
     if (UseParens)
       OS << '(' << Sym << ')';
     else
@@ -65,9 +58,7 @@ void MCExpr::print(raw_ostream &OS) const {
         SRE.getKind() == MCSymbolRefExpr::VK_ARM_TARGET2 ||
         SRE.getKind() == MCSymbolRefExpr::VK_ARM_PREL31)
       OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
-    else if (SRE.getKind() != MCSymbolRefExpr::VK_None &&
-             SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_HA16 &&
-             SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_LO16)
+    else if (SRE.getKind() != MCSymbolRefExpr::VK_None)
       OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
 
     return;
@@ -207,10 +198,8 @@ StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
   case VK_ARM_PREL31: return "(prel31)";
   case VK_PPC_TOC: return "tocbase";
   case VK_PPC_TOC_ENTRY: return "toc";
-  case VK_PPC_DARWIN_HA16: return "ha16";
-  case VK_PPC_DARWIN_LO16: return "lo16";
-  case VK_PPC_GAS_HA16: return "ha";
-  case VK_PPC_GAS_LO16: return "l";
+  case VK_PPC_ADDR16_HA: return "ha";
+  case VK_PPC_ADDR16_LO: return "l";
   case VK_PPC_TPREL16_HA: return "tprel@ha";
   case VK_PPC_TPREL16_LO: return "tprel@l";
   case VK_PPC_DTPREL16_HA: return "dtprel@ha";
@@ -290,10 +279,10 @@ MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
     .Case("imgrel", VK_COFF_IMGREL32)
     .Case("SECREL32", VK_SECREL)
     .Case("secrel32", VK_SECREL)
-    .Case("HA", VK_PPC_GAS_HA16)
-    .Case("ha", VK_PPC_GAS_HA16)
-    .Case("L", VK_PPC_GAS_LO16)
-    .Case("l", VK_PPC_GAS_LO16)
+    .Case("HA", VK_PPC_ADDR16_HA)
+    .Case("ha", VK_PPC_ADDR16_HA)
+    .Case("L", VK_PPC_ADDR16_LO)
+    .Case("l", VK_PPC_ADDR16_LO)
     .Case("TOCBASE", VK_PPC_TOC)
     .Case("tocbase", VK_PPC_TOC)
     .Case("TOC", VK_PPC_TOC_ENTRY)