Add OpSize16 bit, for instructions which need 0x66 prefix in 16-bit mode

The 0x66 prefix toggles between 16-bit and 32-bit addressing mode.
So in 32-bit mode it is used to switch to 16-bit addressing mode for the
following instruction, while in 16-bit mode it's the other way round — it's
used to switch to 32-bit mode instead.

Thus, emit the 0x66 prefix byte for OpSize only in 32-bit (and 64-bit) mode,
and introduce a new OpSize16 bit which is used in 16-bit mode instead.

This is just the basic infrastructure for that change; a subsequent patch
will add the new OpSize16 bit to the 32-bit instructions that need it.

Patch from David Woodhouse.

llvm-svn: 198586

diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h b/llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h
index 9c1ff15..3de5d82 100644 (file)
--- a/llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86BaseInfo.h
@@ -295,13 +295,15 @@ namespace X86II {
 
     // OpSize - Set if this instruction requires an operand size prefix (0x66),
     // which most often indicates that the instruction operates on 16 bit data
-    // instead of 32 bit data.
+    // instead of 32 bit data. OpSize16 in 16 bit mode indicates that the
+    // instruction operates on 32 bit data instead of 16 bit data.
     OpSize      = 1 << 6,
+    OpSize16    = 1 << 7,
 
     // AsSize - Set if this instruction requires an operand size prefix (0x67),
     // which most often indicates that the instruction address 16 bit address
     // instead of 32 bit address (or 32 bit address in 64 bit mode).
-    AdSize      = 1 << 7,
+    AdSize      = 1 << 8,
 
     //===------------------------------------------------------------------===//
     // Op0Mask - There are several prefix bytes that are used to form two byte
@@ -309,7 +311,7 @@ namespace X86II {
     // used to obtain the setting of this field.  If no bits in this field is
     // set, there is no prefix byte for obtaining a multibyte opcode.
     //
-    Op0Shift    = 8,
+    Op0Shift    = 9,
     Op0Mask     = 0x1F << Op0Shift,
 
     // TB - TwoByte - Set if this instruction has a two byte opcode, which

diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
index 51b90b1..06bce46 100644 (file)
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
@@ -1191,8 +1191,7 @@ void X86MCCodeEmitter::EmitOpcodePrefix(uint64_t TSFlags, unsigned &CurByte,
     EmitByte(0x67, CurByte, OS);
 
   // Emit the operand size opcode prefix as needed.
-  // FIXME for is16BitMode().
-  if (TSFlags & X86II::OpSize)
+  if (TSFlags & (is16BitMode(Features) ? X86II::OpSize16 : X86II::OpSize))
     EmitByte(0x66, CurByte, OS);
 
   bool Need0FPrefix = false;

diff --git a/llvm/lib/Target/X86/X86InstrFormats.td b/llvm/lib/Target/X86/X86InstrFormats.td
index 8573991..ea146b2 100644 (file)
--- a/llvm/lib/Target/X86/X86InstrFormats.td
+++ b/llvm/lib/Target/X86/X86InstrFormats.td
@@ -112,6 +112,7 @@ def CD8VT8 : CD8VForm<7>;  // v := 8
 // Prefix byte classes which are used to indicate to the ad-hoc machine code
 // emitter that various prefix bytes are required.
 class OpSize { bit hasOpSizePrefix = 1; }
+class OpSize16 { bit hasOpSize16Prefix = 1; }
 class AdSize { bit hasAdSizePrefix = 1; }
 class REX_W  { bit hasREX_WPrefix = 1; }
 class LOCK   { bit hasLockPrefix = 1; }
@@ -191,6 +192,7 @@ class X86Inst<bits<8> opcod, Format f, ImmType i, dag outs, dag ins,
                             // AsmString from the parser, but still disassemble.
 
   bit hasOpSizePrefix = 0;  // Does this inst have a 0x66 prefix?
+  bit hasOpSize16Prefix = 0;// Does this inst have a 0x66 prefix in 16-bit mode?
   bit hasAdSizePrefix = 0;  // Does this inst have a 0x67 prefix?
 
   bits<5> Prefix = 0;       // Which prefix byte does this inst have?
@@ -222,32 +224,33 @@ class X86Inst<bits<8> opcod, Format f, ImmType i, dag outs, dag ins,
   // TSFlags layout should be kept in sync with X86InstrInfo.h.
   let TSFlags{5-0}   = FormBits;
   let TSFlags{6}     = hasOpSizePrefix;
-  let TSFlags{7}     = hasAdSizePrefix;
-  let TSFlags{12-8}  = Prefix;
-  let TSFlags{13}    = hasREX_WPrefix;
-  let TSFlags{16-14} = ImmT.Value;
-  let TSFlags{19-17} = FPForm.Value;
-  let TSFlags{20}    = hasLockPrefix;
-  let TSFlags{22-21} = SegOvrBits;
-  let TSFlags{24-23} = ExeDomain.Value;
-  let TSFlags{32-25} = Opcode;
-  let TSFlags{33}    = hasVEXPrefix;
-  let TSFlags{34}    = hasVEX_WPrefix;
-  let TSFlags{35}    = hasVEX_4VPrefix;
-  let TSFlags{36}    = hasVEX_4VOp3Prefix;
-  let TSFlags{37}    = hasVEX_i8ImmReg;
-  let TSFlags{38}    = hasVEX_L;
-  let TSFlags{39}    = ignoresVEX_L;
-  let TSFlags{40}    = hasEVEXPrefix;
-  let TSFlags{41}    = hasEVEX_K;
-  let TSFlags{42}    = hasEVEX_Z;
-  let TSFlags{43}    = hasEVEX_L2;
-  let TSFlags{44}    = hasEVEX_B;
-  let TSFlags{46-45} = EVEX_CD8E;
-  let TSFlags{49-47} = EVEX_CD8V;
-  let TSFlags{50}    = has3DNow0F0FOpcode;
-  let TSFlags{51}    = hasMemOp4Prefix;
-  let TSFlags{52}    = hasXOP_Prefix;
+  let TSFlags{7}     = hasOpSize16Prefix;
+  let TSFlags{8}     = hasAdSizePrefix;
+  let TSFlags{13-9}  = Prefix;
+  let TSFlags{14}    = hasREX_WPrefix;
+  let TSFlags{17-15} = ImmT.Value;
+  let TSFlags{20-18} = FPForm.Value;
+  let TSFlags{21}    = hasLockPrefix;
+  let TSFlags{23-22} = SegOvrBits;
+  let TSFlags{25-24} = ExeDomain.Value;
+  let TSFlags{33-26} = Opcode;
+  let TSFlags{34}    = hasVEXPrefix;
+  let TSFlags{35}    = hasVEX_WPrefix;
+  let TSFlags{36}    = hasVEX_4VPrefix;
+  let TSFlags{37}    = hasVEX_4VOp3Prefix;
+  let TSFlags{38}    = hasVEX_i8ImmReg;
+  let TSFlags{39}    = hasVEX_L;
+  let TSFlags{40}    = ignoresVEX_L;
+  let TSFlags{41}    = hasEVEXPrefix;
+  let TSFlags{42}    = hasEVEX_K;
+  let TSFlags{43}    = hasEVEX_Z;
+  let TSFlags{44}    = hasEVEX_L2;
+  let TSFlags{45}    = hasEVEX_B;
+  let TSFlags{47-46} = EVEX_CD8E;
+  let TSFlags{50-48} = EVEX_CD8V;
+  let TSFlags{51}    = has3DNow0F0FOpcode;
+  let TSFlags{52}    = hasMemOp4Prefix;
+  let TSFlags{53}    = hasXOP_Prefix;
 }
 
 class PseudoI<dag oops, dag iops, list<dag> pattern>

diff --git a/llvm/test/MC/X86/x86-16.s b/llvm/test/MC/X86/x86-16.s
index 36f3b19..115132d 100644 (file)
--- a/llvm/test/MC/X86/x86-16.s
+++ b/llvm/test/MC/X86/x86-16.s
@@ -27,6 +27,9 @@
 // CHECK: testb        %bl, %cl                # encoding: [0x84,0xcb]
         testb %bl, %cl
 
+// CHECK: addw %ax, %ax                # encoding: [0x01,0xc0]
+        addw %ax, %ax
+
 into
 // CHECK: into
 // CHECK:  encoding: [0xce]
@@ -40,6 +43,10 @@ int $255
 // CHECK: int $255
 // CHECK:  encoding: [0xcd,0xff]
 
+// CHECK: cmovbw %bx, %bx
+cmovnae        %bx,%bx
+
+
 // CHECK: fmul %st(0)
 // CHECK:  encoding: [0xd8,0xc8]
         fmul %st(0), %st
@@ -64,10 +71,119 @@ int $255
 // CHECK:  encoding: [0xd8,0xf0]
         fdiv %st(0), %st
 
+// CHECK: movw %cs, %ax
+// CHECK:  encoding: [0x8c,0xc8]
+        movw %cs, %ax
+
+// CHECK: movw %cs, (%eax)
+// CHECK:  encoding: [0x67,0x8c,0x08]
+        movw %cs, (%eax)
+
+// CHECK: movw (%eax), %cs
+// CHECK:  encoding: [0x67,0x8e,0x08]
+        movw (%eax), %cs
+
+// CHECK: movl %cr0, %eax
+// CHECK:  encoding: [0x0f,0x20,0xc0]
+        movl %cr0,%eax
+
+// CHECK: movl %cr1, %eax
+// CHECK:  encoding: [0x0f,0x20,0xc8]
+        movl %cr1,%eax
+
+// CHECK: movl %cr2, %eax
+// CHECK:  encoding: [0x0f,0x20,0xd0]
+        movl %cr2,%eax
+
+// CHECK: movl %cr3, %eax
+// CHECK:  encoding: [0x0f,0x20,0xd8]
+        movl %cr3,%eax
+
+// CHECK: movl %cr4, %eax
+// CHECK:  encoding: [0x0f,0x20,0xe0]
+        movl %cr4,%eax
+
+// CHECK: movl %dr0, %eax
+// CHECK:  encoding: [0x0f,0x21,0xc0]
+        movl %dr0,%eax
+
+// CHECK: movl %dr1, %eax
+// CHECK:  encoding: [0x0f,0x21,0xc8]
+        movl %dr1,%eax
+
+// CHECK: movl %dr1, %eax
+// CHECK:  encoding: [0x0f,0x21,0xc8]
+        movl %dr1,%eax
+
+// CHECK: movl %dr2, %eax
+// CHECK:  encoding: [0x0f,0x21,0xd0]
+        movl %dr2,%eax
+
+// CHECK: movl %dr3, %eax
+// CHECK:  encoding: [0x0f,0x21,0xd8]
+        movl %dr3,%eax
+
+// CHECK: movl %dr4, %eax
+// CHECK:  encoding: [0x0f,0x21,0xe0]
+        movl %dr4,%eax
+
+// CHECK: movl %dr5, %eax
+// CHECK:  encoding: [0x0f,0x21,0xe8]
+        movl %dr5,%eax
+
+// CHECK: movl %dr6, %eax
+// CHECK:  encoding: [0x0f,0x21,0xf0]
+        movl %dr6,%eax
+
+// CHECK: movl %dr7, %eax
+// CHECK:  encoding: [0x0f,0x21,0xf8]
+        movl %dr7,%eax
+
 // CHECK: wait
 // CHECK:  encoding: [0x9b]
        fwait
 
+sysret
+// CHECK: sysretl
+// CHECK: encoding: [0x0f,0x07]
+sysretl
+// CHECK: sysretl
+// CHECK: encoding: [0x0f,0x07]
+
+testl  %ecx, -24(%ebp)
+// CHECK: testl        -24(%ebp), %ecx
+testl  -24(%ebp), %ecx
+// CHECK: testl        -24(%ebp), %ecx
+
+
+pushw %cs
+// CHECK: pushw        %cs
+// CHECK: encoding: [0x0e]
+pushw %ds
+// CHECK: pushw        %ds
+// CHECK: encoding: [0x1e]
+pushw %ss
+// CHECK: pushw        %ss
+// CHECK: encoding: [0x16]
+pushw %es
+// CHECK: pushw        %es
+// CHECK: encoding: [0x06]
+pushw %fs
+// CHECK: pushw        %fs
+// CHECK: encoding: [0x0f,0xa0]
+pushw %gs
+// CHECK: pushw        %gs
+// CHECK: encoding: [0x0f,0xa8]
+
+pushfd
+// CHECK: pushfl
+popfd
+// CHECK: popfl
+pushfl
+// CHECK: pushfl
+popfl
+// CHECK: popfl
+
 
        setc    %bl
        setnae  %bl
@@ -103,9 +219,15 @@ ljmpl      $0x7ace,$0x7ace
 // CHECK:      incb    %al # encoding: [0xfe,0xc0]
        incb %al
 
+// CHECK:      incw    %ax # encoding: [0x40]
+       incw %ax
+
 // CHECK:      decb    %al # encoding: [0xfe,0xc8]
        decb %al
 
+// CHECK:      decw    %ax # encoding: [0x48]
+       decw %ax
+
 // CHECK: pshufw $14, %mm4, %mm0 # encoding: [0x0f,0x70,0xc4,0x0e]
 pshufw $14, %mm4, %mm0
 
@@ -152,6 +274,10 @@ pshufw $90, %mm4, %mm0
 // CHECK:  encoding: [0x2f]
                das
 
+// CHECK: bound        2(%eax), %bx
+// CHECK:  encoding: [0x67,0x62,0x58,0x02]
+               bound   2(%eax),%bx
+
 // CHECK: arpl %bx, %bx
 // CHECK:  encoding: [0x63,0xdb]
                arpl    %bx,%bx
@@ -219,11 +345,23 @@ pshufw $90, %mm4, %mm0
        outsb   %ds:(%si), %dx
        outsb   (%si), %dx
 
+// CHECK: outsw # encoding: [0x6f]
+// CHECK: outsw
+// CHECK: outsw
+       outsw
+       outsw   %ds:(%si), %dx
+       outsw   (%si), %dx
+
 // CHECK: insb # encoding: [0x6c]
 // CHECK: insb
        insb
        insb    %dx, %es:(%di)
 
+// CHECK: insw # encoding: [0x6d]
+// CHECK: insw
+       insw
+       insw    %dx, %es:(%di)
+
 // CHECK: movsb # encoding: [0xa4]
 // CHECK: movsb
 // CHECK: movsb
@@ -231,6 +369,13 @@ pshufw $90, %mm4, %mm0
        movsb   %ds:(%si), %es:(%di)
        movsb   (%si), %es:(%di)
 
+// CHECK: movsw # encoding: [0xa5]
+// CHECK: movsw
+// CHECK: movsw
+       movsw
+       movsw   %ds:(%si), %es:(%di)
+       movsw   (%si), %es:(%di)
+
 // CHECK: lodsb # encoding: [0xac]
 // CHECK: lodsb
 // CHECK: lodsb
@@ -242,6 +387,17 @@ pshufw $90, %mm4, %mm0
        lods    %ds:(%si), %al
        lods    (%si), %al
 
+// CHECK: lodsw # encoding: [0xad]
+// CHECK: lodsw
+// CHECK: lodsw
+// CHECK: lodsw
+// CHECK: lodsw
+       lodsw
+       lodsw   %ds:(%si), %ax
+       lodsw   (%si), %ax
+       lods    %ds:(%si), %ax
+       lods    (%si), %ax
+
 // CHECK: stosb # encoding: [0xaa]
 // CHECK: stosb
 // CHECK: stosb
@@ -249,6 +405,17 @@ pshufw $90, %mm4, %mm0
        stosb   %al, %es:(%di)
        stos    %al, %es:(%di)
 
+// CHECK: stosw # encoding: [0xab]
+// CHECK: stosw
+// CHECK: stosw
+       stosw
+       stosw   %ax, %es:(%di)
+       stos    %ax, %es:(%di)
+
+// CHECK: strw
+// CHECK: encoding: [0x0f,0x00,0xc8]
+       str %ax
+
 // CHECK: fsubp
 // CHECK: encoding: [0xde,0xe1]
 fsubp %st,%st(1)
@@ -257,3 +424,6 @@ fsubp %st,%st(1)
 // CHECK: encoding: [0xde,0xe2]
 fsubp   %st, %st(2)
 
+// CHECK: xchgw %ax, %ax
+// CHECK: encoding: [0x90]
+xchgw %ax, %ax