[mips] Extend MipsAsmParser class to handle expressions in the %tprel / %dtprel relocations

[atanasyan]

Summary

Now the asm parser supports %tprel_hi/lo and %dtprel_hi/lo relocations with a symbol argument only. But expressions like sym + const are valid also and accepted by GAS.

[atanasyan]

Do not right shift addend for DTPREL_HI and TPREL_HI relocations to mimics GAS behavior and LD expectations.

[atanasyan]

Ping?

[atanasyan]

Ping?

[dsanders]

Sorry for the delay in looking at this. I wasn't able to comment until I'd found some information on how they were expected to behave.

I see you've just abandoned the revision but it LGTM on the basis that the odd addends work the same way as GAS does.

test/MC/Mips/tprel-hi-lo-expr.s

10

GAS does the same thing but is this addend really correct? I'd have expected to get 'lui $3, 0' since the offset is in the low 16-bits but '$loc0+0x7ffc' seems to be interpreted as '$loc0+0x7ffc0000'

lib/Target/Mips/AsmParser/MipsAsmParser.cpp

if (const MCConstantExpr *MCE = dyn_cast<MCConstantExpr>(Expr)) {
     case MCSymbolRefExpr::VK_Mips_HIGHER:
       // Get the 3rd 16-bits.
       Val = ((MCE->getValue() + 0x80008000LL) >> 32) & 0xffff;
       break;
     case MCSymbolRefExpr::VK_Mips_HIGHEST:
       // Get the 4th 16-bits.
       Val = ((MCE->getValue() + 0x800080008000LL) >> 48) & 0xffff;
       break;
+    case MCSymbolRefExpr::VK_Mips_DTPREL_HI:
+    case MCSymbolRefExpr::VK_Mips_TPREL_HI:
+    case MCSymbolRefExpr::VK_Mips_DTPREL_LO:
+    case MCSymbolRefExpr::VK_Mips_TPREL_LO:
+      // Get the 16-bits for both 'hi' and 'lo' relocations.
+      // TPREL and DTPREL relocations do not use combined addend calculated
+      // using both HI and LO parts like %hi and %lo do.
+      Val = MCE->getValue() & 0xffff;
+      break;
     default:
       report_fatal_error("unsupported reloc value");
     }
     return MCConstantExpr::create(Val, getContext());
   }
 
   if (const MCSymbolRefExpr *MSRE = dyn_cast<MCSymbolRefExpr>(Expr)) {
     // It's a symbol, create a symbolic expression from the symbol.

test/MC/Mips/tprel-hi-lo-expr.s

+# Check that llvm-mc accepts arithmetic expression as an argument
+# of the %tprel_hi, %tprel_lo relocations.
+
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s \
+# RUN:   | llvm-objdump -d -r - | FileCheck %s
+
+  .text
+foo:
+  lui     $3,%tprel_hi($loc0+0x7ffc)
+# CHECK: 0:       3c 03 7f fc     lui   $3, 32764
+# CHECK:                  00000000:  R_MIPS_TLS_TPREL_HI16    $loc0
+  addiu   $3,$3,%tprel_lo($loc0+0x7ffc)
+# CHECK: 4:       24 63 7f fc     addiu $3, $3, 32764
+# CHECK:                  00000004:  R_MIPS_TLS_TPREL_LO16    $loc0
+  lui     $3,%dtprel_hi($loc0+0x7ffc)
+# CHECK: 8:       3c 03 7f fc     lui   $3, 32764
+# CHECK:                  00000008:  R_MIPS_TLS_DTPREL_HI16   $loc0
+  addiu   $3,$3,%dtprel_lo($loc0+0x7ffc)
+# CHECK: c:       24 63 7f fc     addiu $3, $3, 32764
+# CHECK:                  0000000c:  R_MIPS_TLS_DTPREL_LO16   $loc0
+
+  .section .tdata,"awT",%progbits
+$loc0:
+  .word 0
+  .space 0x8000