[PATCH] [mips] [IAS] Fix expansion of negative 32-bit immediates for LI/DLI.

[Daniel Sanders]

With a couple corrections it will LGTM


================
Comment at: lib/Target/Mips/AsmParser/MipsAsmParser.cpp:1762
@@ -1761,5 +1761,3 @@
 
-    tmpInst.setOpcode(Mips::LUi);
-    tmpInst.addOperand(MCOperand::CreateReg(DstReg));
-    tmpInst.addOperand(MCOperand::CreateImm(Bits31To16));
-    Instructions.push_back(tmpInst);
+    if (!Is32BitImm && isUInt<32>(ImmValue)) {
+      // For DLI, expand to an ORi instead of a LUi to avoid sign-extending the
----------------
This isn't quite right. You need to check for ``!isInt<32>(ImmValue)``. That way it will use lui+ori except when it really needs to use ori+dslli+ori such as for 0x80000000.

You'll also need a test to cover this once the check is corrected.

================
Comment at: test/MC/Mips/mips64-expansions.s:13-14
@@ -12,3 +12,4 @@
   dli $7, 65538
-# CHECK:     lui   $7, 1            # encoding: [0x01,0x00,0x07,0x3c]
+# CHECK:     ori   $7, $zero, 1     # encoding: [0x01,0x00,0x07,0x34]
+# CHECK:     dsll  $7, $7, 16       # encoding: [0x38,0x3c,0x07,0x00]
 # CHECK:     ori   $7, $7, 2        # encoding: [0x02,0x00,0xe7,0x34]
----------------
This was correct before. 0x10002 should use:
lui ..., 0x1
ori ..., ..., 0x2

================
Comment at: test/MC/Mips/mips64-expansions.s:21-22
@@ -19,3 +20,4 @@
   dli $9, 0x10000
-# CHECK:     lui   $9, 1            # encoding: [0x01,0x00,0x09,0x3c]
+# CHECK:     ori   $9, $zero, 1     # encoding: [0x01,0x00,0x09,0x34]
+# CHECK:     dsll  $9, $9, 16       # encoding: [0x38,0x4c,0x09,0x00]
 # CHECK-NOT: ori   $9, $9, 0        # encoding: [0x00,0x00,0x29,0x35]
----------------
This was correct before. 0x10000 should use
lui ..., 0x1

http://reviews.llvm.org/D8662

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