[llvm] r188549 - Add support for Thumb2 literal loads with negative zero offset

[Mihai Popa]

Author: mpopa
Date: Fri Aug 16 07:03:00 2013
New Revision: 188549

URL: http://llvm.org/viewvc/llvm-project?rev=188549&view=rev
Log:
Add support for Thumb2 literal loads with negative zero offset

Thumb2 literal loads use an offset encoding which allows for 
negative zero. This fixes parsing and encoding so that #-0 
is correctly processed. The parser represents #-0 as INT32_MIN.


Modified:
    llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
    llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
    llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s

Modified: llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp?rev=188549&r1=188548&r2=188549&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp (original)
+++ llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp Fri Aug 16 07:03:00 2013
@@ -1793,8 +1793,6 @@ public:
   void addMemPCRelImm12Operands(MCInst &Inst, unsigned N) const {
     assert(N == 1 && "Invalid number of operands!");
     int32_t Imm = Memory.OffsetImm->getValue();
-    // FIXME: Handle #-0
-    if (Imm == INT32_MIN) Imm = 0;
     Inst.addOperand(MCOperand::CreateImm(Imm));
   }
 

Modified: llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp?rev=188549&r1=188548&r2=188549&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp (original)
+++ llvm/trunk/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp Fri Aug 16 07:03:00 2013
@@ -778,8 +778,10 @@ getAddrModeImm12OpValue(const MCInst &MI
     } else {
       Reg = ARM::PC;
       int32_t Offset = MO.getImm();
-      // FIXME: Handle #-0.
-      if (Offset < 0) {
+      if (Offset == INT32_MIN) {
+        Offset = 0;
+        isAdd = false;
+      } else if (Offset < 0) {
         Offset *= -1;
         isAdd = false;
       }

Modified: llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s?rev=188549&r1=188548&r2=188549&view=diff
==============================================================================
--- llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s (original)
+++ llvm/trunk/test/MC/ARM/basic-thumb2-instructions.s Fri Aug 16 07:03:00 2013
@@ -830,6 +830,18 @@ _func:
 @ CHECK: ldr.w	pc, [pc, #256]          @ encoding: [0xdf,0xf8,0x00,0xf1]
 @ CHECK: ldr.w	pc, [pc, #-400]         @ encoding: [0x5f,0xf8,0x90,0xf1]
 
+        ldrb  r9, [pc, #-0]
+        ldrsb r11, [pc, #-0]
+        ldrh  r10, [pc, #-0]
+        ldrsh r1, [pc, #-0]
+        ldr   r5, [pc, #-0]
+
+@ CHECK: ldrb.w	r9, [pc, #-0]           @ encoding: [0x1f,0xf8,0x00,0x90]
+@ CHECK: ldrsb.w	r11, [pc, #-0]        @ encoding: [0x1f,0xf9,0x00,0xb0]
+@ CHECK: ldrh.w	r10, [pc, #-0]          @ encoding: [0x3f,0xf8,0x00,0xa0]
+@ CHECK: ldrsh.w	r1, [pc, #-0]         @ encoding: [0x3f,0xf9,0x00,0x10]
+@ CHECK: ldr.w	r5, [pc, #-0]           @ encoding: [0x5f,0xf8,0x00,0x50]
+
 @------------------------------------------------------------------------------
 @ LDR(register)
 @------------------------------------------------------------------------------