[mips] Extend MipsAsmParser class to handle %got(sym + const) expressions

Now the parser supports `%got(sym)` expressions only but `%got(sym + const)`
variant is also valid and accepted by GAS.

Differential Revision: http://reviews.llvm.org/D16885

llvm-svn: 260305

llvm/lib/Target/Mips/AsmParser/MipsAsmParser.cpp

@@ -4018,6 +4018,7 @@ const MCExpr *MipsAsmParser::evaluateRelocExpr(const MCExpr *Expr,
       Val = MCE->getValue() & 0xffff;
       break;
     case MCSymbolRefExpr::VK_Mips_ABS_HI:
+    case MCSymbolRefExpr::VK_Mips_GOT:
       // Get the 2nd 16-bits. Also add 1 if bit 15 is 1, to compensate for low
       // 16 bits being negative.
       Val = ((MCE->getValue() + 0x8000) >> 16) & 0xffff;

llvm/test/MC/Mips/got-rel-expr.s

@@ -0,0 +1,20 @@
+# Check that llvm-mc accepts arithmetic expression
+# as an argument of the %got relocation.
+
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s \
+# RUN:   | llvm-objdump -d -r - | FileCheck %s
+
+  .text
+foo:
+  lw      $t0,%got($loc+0x10004)($gp)
+# CHECK: 0:       8f 88 00 01     lw      $8, 1($gp)
+# CHECK:                  00000000:  R_MIPS_GOT16 $loc
+  addi    $t0,$t0,%lo($loc+0x10004)
+# CHECK: 4:       21 08 00 04     addi    $8, $8, 4
+# CHECK:                  00000004:  R_MIPS_LO16  $loc
+
+  .data
+$loc:
+  .word 0
+  .space 0x10000
+  .word 0