[llvm-commits] [llvm] r138862 - in /llvm/trunk: lib/Target/ARM/AsmParser/ARMAsmParser.cpp test/MC/ARM/basic-thumb-instructions.s

[Jim Grosbach]

Author: grosbach
Date: Wed Aug 31 12:07:33 2011
New Revision: 138862

URL: http://llvm.org/viewvc/llvm-project?rev=138862&view=rev
Log:
Tweak Thumb1 ADD encoding selection a bit.

When the destination register of an add immediate instruction is
explicitly specified, encoding T1 is preferred, else encoding T2 is
preferred.

Modified:
    llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
    llvm/trunk/test/MC/ARM/basic-thumb-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=138862&r1=138861&r2=138862&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp (original)
+++ llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp Wed Aug 31 12:07:33 2011
@@ -3473,8 +3473,11 @@
     }
     break;
   case ARM::tADDi8:
-    // If the immediate is in the range 0-7, we really wanted tADDi3.
-    if (Inst.getOperand(3).getImm() < 8)
+    // If the immediate is in the range 0-7, we want tADDi3 iff Rd was
+    // explicitly specified. From the ARM ARM: "Encoding T1 is preferred
+    // to encoding T2 if <Rd> is specified and encoding T2 is preferred
+    // to encoding T1 if <Rd> is omitted."
+    if (Inst.getOperand(3).getImm() < 8 && Operands.size() == 6)
       Inst.setOpcode(ARM::tADDi3);
     break;
   case ARM::tBcc:

Modified: llvm/trunk/test/MC/ARM/basic-thumb-instructions.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/basic-thumb-instructions.s?rev=138862&r1=138861&r2=138862&view=diff
==============================================================================
--- llvm/trunk/test/MC/ARM/basic-thumb-instructions.s (original)
+++ llvm/trunk/test/MC/ARM/basic-thumb-instructions.s Wed Aug 31 12:07:33 2011
@@ -26,11 +26,13 @@
 @ ADD (immediate)
 @------------------------------------------------------------------------------
         adds r1, r2, #3
+@ When Rd is not explicitly specified, encoding T2 is preferred even though
+@ the literal is in the range [0,7] which would allow encoding T1.
         adds r2, #3
         adds r2, #8
 
 @ CHECK: adds	r1, r2, #3              @ encoding: [0xd1,0x1c]
-@ CHECK: adds	r2, r2, #3              @ encoding: [0xd2,0x1c]
+@ CHECK: adds	r2, #3                  @ encoding: [0x03,0x32]
 @ CHECK: adds	r2, #8                  @ encoding: [0x08,0x32]