Add instruction encoding for the Neon VMOV immediate instruction. This changes

the machine instruction representation of the immediate value to be encoded
into an integer with similar fields as the actual VMOV instruction.  This makes
things easier for the disassembler, since it can just stuff the bits into the
immediate operand, but harder for the asm printer since it has to decode the
value to be printed.  Testcase for the encoding will follow later when MC has
more support for ARM.

llvm-svn: 105836

1 files changed, 32 insertions, 18 deletions

diff --git a/llvm/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp b/llvm/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp
index 2b94b76087e..b59852ebfcb 100644
--- a/llvm/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp
+++ b/llvm/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp
@@ -779,22 +779,36 @@ void ARMInstPrinter::printVFPf64ImmOperand(const MCInst *MI, unsigned OpNum,
   O << '#' << MI->getOperand(OpNum).getImm();
 }
 
-void ARMInstPrinter::printHex8ImmOperand(const MCInst *MI, unsigned OpNum,
-                                         raw_ostream &O) {
-  O << "#0x" << utohexstr(MI->getOperand(OpNum).getImm() & 0xff);
-}
-
-void ARMInstPrinter::printHex16ImmOperand(const MCInst *MI, unsigned OpNum,
-                                          raw_ostream &O) {
-  O << "#0x" << utohexstr(MI->getOperand(OpNum).getImm() & 0xffff);
-}
-
-void ARMInstPrinter::printHex32ImmOperand(const MCInst *MI, unsigned OpNum,
-                                          raw_ostream &O) {
-  O << "#0x" << utohexstr(MI->getOperand(OpNum).getImm() & 0xffffffff);
-}
-
-void ARMInstPrinter::printHex64ImmOperand(const MCInst *MI, unsigned OpNum,
-                                          raw_ostream &O) {
-  O << "#0x" << utohexstr(MI->getOperand(OpNum).getImm());
+void ARMInstPrinter::printNEONModImmOperand(const MCInst *MI, unsigned OpNum,
+                                            raw_ostream &O) {
+  unsigned Imm = MI->getOperand(OpNum).getImm();
+  unsigned OpCmode = (Imm >> 8) & 0x1f;
+  unsigned Imm8 = Imm & 0xff;
+  uint64_t Val = 0;
+
+  if (OpCmode == 0xe) {
+    // 8-bit vector elements
+    Val = Imm8;
+  } else if ((OpCmode & 0xc) == 0x8) {
+    // 16-bit vector elements
+    unsigned ByteNum = (OpCmode & 0x6) >> 1;
+    Val = Imm8 << (8 * ByteNum);
+  } else if ((OpCmode & 0x8) == 0) {
+    // 32-bit vector elements, zero with one byte set
+    unsigned ByteNum = (OpCmode & 0x6) >> 1;
+    Val = Imm8 << (8 * ByteNum);
+  } else if ((OpCmode & 0xe) == 0xc) {
+    // 32-bit vector elements, one byte with low bits set
+    unsigned ByteNum = (OpCmode & 0x1);
+    Val = (Imm8 << (8 * ByteNum)) | (0xffff >> (8 * (1 - ByteNum)));
+  } else if (OpCmode == 0x1e) {
+    // 64-bit vector elements
+    for (unsigned ByteNum = 0; ByteNum < 8; ++ByteNum) {
+      if ((Imm >> ByteNum) & 1)
+        Val |= (uint64_t)0xff << (8 * ByteNum);
+    }
+  } else {
+    assert(false && "Unsupported NEON immediate");
+  }
+  O << "#0x" << utohexstr(Val);
 }