[PATCH] [mips] [IAS] Fix creation of MCSymbolRefExpr's of $tmp symbols in evaluateRelocExpr().

[Toma Tabacu]

Hi dsanders,

Previously, MCSymbolRefExpr::Create() was called with a StringRef of the symbol name, which it would then search for in the Symbols StringMap (from MCContext).

However, $tmp symbols are (apparently) not stored in the Symbols StringMap, so we end up creating a new $tmp symbol ($tmp00, $tmp10 etc.) each time we create
an MCSymbolRefExpr by passing in the symbol name as a StringRef.

Fortunately, there is a version of MCSymbolRefExpr::Create() which takes an MCSymbol* and we already have an MCSymbol* at that point in evaluateRelocExpr(),
so we can just pass that in instead of the StringRef.

I also replaced the bad manual calls to MCSymbolRefExpr::Create() from expandMemInst() with calls to evaluateRelocExpr().
At the moment, expandLoadAddressSym() also has bad manual calls to MCSymbolRefExpr::Create(), but I didn't fix those because they're going to be
changed to evaluateRelocExpr() soon anyway (by D9344).

http://reviews.llvm.org/D9938

Files:
  lib/Target/Mips/AsmParser/MipsAsmParser.cpp
  test/MC/Mips/mips-expansions.s

Index: lib/Target/Mips/AsmParser/MipsAsmParser.cpp
===================================================================
--- lib/Target/Mips/AsmParser/MipsAsmParser.cpp
+++ lib/Target/Mips/AsmParser/MipsAsmParser.cpp
@@ -2029,7 +2029,6 @@
 void MipsAsmParser::expandMemInst(MCInst &Inst, SMLoc IDLoc,
                                   SmallVectorImpl<MCInst> &Instructions,
                                   bool isLoad, bool isImmOpnd) {
-  const MCSymbolRefExpr *SR;
   MCInst TempInst;
   unsigned ImmOffset, HiOffset, LoOffset;
   const MCExpr *ExprOffset;
@@ -2096,16 +2095,8 @@
   if (isImmOpnd)
     TempInst.addOperand(MCOperand::createImm(HiOffset));
   else {
-    if (ExprOffset->getKind() == MCExpr::SymbolRef) {
-      SR = static_cast<const MCSymbolRefExpr *>(ExprOffset);
-      const MCSymbolRefExpr *HiExpr = MCSymbolRefExpr::Create(
-          SR->getSymbol().getName(), MCSymbolRefExpr::VK_Mips_ABS_HI,
-          getContext());
-      TempInst.addOperand(MCOperand::createExpr(HiExpr));
-    } else {
-      const MCExpr *HiExpr = evaluateRelocExpr(ExprOffset, "hi");
-      TempInst.addOperand(MCOperand::createExpr(HiExpr));
-    }
+    const MCExpr *HiExpr = evaluateRelocExpr(ExprOffset, "hi");
+    TempInst.addOperand(MCOperand::createExpr(HiExpr));
   }
   // Add the instruction to the list.
   Instructions.push_back(TempInst);
@@ -2128,15 +2119,8 @@
   if (isImmOpnd)
     TempInst.addOperand(MCOperand::createImm(LoOffset));
   else {
-    if (ExprOffset->getKind() == MCExpr::SymbolRef) {
-      const MCSymbolRefExpr *LoExpr = MCSymbolRefExpr::Create(
-          SR->getSymbol().getName(), MCSymbolRefExpr::VK_Mips_ABS_LO,
-          getContext());
-      TempInst.addOperand(MCOperand::createExpr(LoExpr));
-    } else {
-      const MCExpr *LoExpr = evaluateRelocExpr(ExprOffset, "lo");
-      TempInst.addOperand(MCOperand::createExpr(LoExpr));
-    }
+    const MCExpr *LoExpr = evaluateRelocExpr(ExprOffset, "lo");
+    TempInst.addOperand(MCOperand::createExpr(LoExpr));
   }
   Instructions.push_back(TempInst);
   TempInst.clear();
@@ -2566,7 +2550,7 @@
 
   if (const MCSymbolRefExpr *MSRE = dyn_cast<MCSymbolRefExpr>(Expr)) {
     // It's a symbol, create a symbolic expression from the symbol.
-    StringRef Symbol = MSRE->getSymbol().getName();
+    const MCSymbol *Symbol = &MSRE->getSymbol();
     MCSymbolRefExpr::VariantKind VK = getVariantKind(RelocStr);
     Res = MCSymbolRefExpr::Create(Symbol, VK, getContext());
     return Res;
Index: test/MC/Mips/mips-expansions.s
===================================================================
--- test/MC/Mips/mips-expansions.s
+++ test/MC/Mips/mips-expansions.s
@@ -35,6 +35,10 @@
 # CHECK: addu    $1, $1, $9              # encoding: [0x21,0x08,0x29,0x00]
 # CHECK: sw      $10, %lo(symbol)($1)    # encoding: [A,A,0x2a,0xac]
 # CHECK:                                 #   fixup A - offset: 0, value: symbol at ABS_LO, kind: fixup_Mips_LO16
+# CHECK: lui $8, %hi($tmp0)              # encoding: [A,A,0x08,0x3c]
+# CHECK:                                 #   fixup A - offset: 0, value: ($tmp0)@ABS_HI, kind: fixup_Mips_HI16
+# CHECK: lw  $8, %lo($tmp0)($8)          # encoding: [A,A,0x08,0x8d]
+# CHECK:                                 #   fixup A - offset: 0, value: ($tmp0)@ABS_LO, kind: fixup_Mips_LO16
 # CHECK: lui     $10, 10                 # encoding: [0x0a,0x00,0x0a,0x3c]
 # CHECK: addu    $10, $10, $4            # encoding: [0x21,0x50,0x44,0x01]
 # CHECK: lw      $10, 123($10)           # encoding: [0x7b,0x00,0x4a,0x8d]
@@ -76,11 +80,16 @@
     .set at
     sw  $t2, symbol($t1)
 
+    lw $8, 1f
+
     lw  $t2, 655483($a0)
     sw  $t2, 123456($t1)
 
     lw  $8, symbol
     sw  $8, symbol
 
     ldc1 $f0, symbol
     sdc1 $f0, symbol
+
+1:
+    add $4, $4, $4

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