Thumb2 ldr pc-relative encoding fixes.

We were parsing label references to the i12 encoding, which isn't right.
They need to go to the pci variant instead.

More of rdar://10348687

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143068 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/ARM/ARMInstrThumb2.td

@@ -1460,7 +1460,7 @@ def t2STRD_POST : T2Ii8s4post<0, 1, 0, (outs GPR:$wb),
                  "$addr.base = $wb", []>;
 
 // T2Ipl (Preload Data/Instruction) signals the memory system of possible future
-// data/instruction access.  These are for disassembly only.
+// data/instruction access.
 // instr_write is inverted for Thumb mode: (prefetch 3) -> (preload 0),
 // (prefetch 1) -> (preload 2),  (prefetch 2) -> (preload 1).
 multiclass T2Ipl<bits<1> write, bits<1> instr, string opc> {
@@ -1518,6 +1518,10 @@ multiclass T2Ipl<bits<1> write, bits<1> instr, string opc> {
 
     let DecoderMethod = "DecodeT2LoadShift";
   }
+  // FIXME: We should have a separate 'pci' variant here. As-is we represent
+  // it via the i12 variant, which it's related to, but that means we can
+  // represent negative immediates, which aren't legal for anything except
+  // the 'pci' case (Rn == 15).
 }
 
 defm t2PLD  : T2Ipl<0, 0, "pld">,  Requires<[IsThumb2]>;
@@ -3906,6 +3910,17 @@ def : t2InstAlias<"ldrsb${p} $Rt, $addr",
 def : t2InstAlias<"ldrsh${p} $Rt, $addr",
                   (t2LDRSHs rGPR:$Rt, t2addrmode_so_reg:$addr, pred:$p)>;
 
+def : t2InstAlias<"ldr${p} $Rt, $addr",
+                  (t2LDRpci GPR:$Rt, t2ldrlabel:$addr, pred:$p)>;
+def : t2InstAlias<"ldrb${p} $Rt, $addr",
+                  (t2LDRBpci rGPR:$Rt, t2ldrlabel:$addr, pred:$p)>;
+def : t2InstAlias<"ldrh${p} $Rt, $addr",
+                  (t2LDRHpci rGPR:$Rt, t2ldrlabel:$addr, pred:$p)>;
+def : t2InstAlias<"ldrsb${p} $Rt, $addr",
+                  (t2LDRSBpci rGPR:$Rt, t2ldrlabel:$addr, pred:$p)>;
+def : t2InstAlias<"ldrsh${p} $Rt, $addr",
+                  (t2LDRSHpci rGPR:$Rt, t2ldrlabel:$addr, pred:$p)>;
+
 // Alias for MVN without the ".w" optional width specifier.
 def : t2InstAlias<"mvn${s}${p} $Rd, $Rm",
            (t2MVNr rGPR:$Rd, rGPR:$Rm, pred:$p, cc_out:$s)>;

lib/Target/ARM/AsmParser/ARMAsmParser.cpp

@@ -865,12 +865,6 @@ public:
     return Val > -256 && Val < 0;
   }
   bool isMemUImm12Offset() const {
-    // If we have an immediate that's not a constant, treat it as a label
-    // reference needing a fixup. If it is a constant, it's something else
-    // and we reject it.
-    if (Kind == k_Immediate && !isa<MCConstantExpr>(getImm()))
-      return true;
-
     if (!isMemory() || Memory.OffsetRegNum != 0 || Memory.Alignment != 0)
       return false;
     // Immediate offset in range [0, 4095].

test/MC/ARM/basic-thumb2-instructions.s

@@ -638,9 +638,12 @@ _func:
 @ LDR(literal)
 @------------------------------------------------------------------------------
         ldr.w r5, _foo
+        ldr   lr, (_strcmp-4)
 
 @ CHECK: ldr.w	r5, _foo                @ encoding: [0x5f'A',0xf8'A',A,0x50'A']
-            @   fixup A - offset: 0, value: _foo, kind: fixup_t2_ldst_pcrel_12
+@ CHECK: @   fixup A - offset: 0, value: _foo, kind: fixup_t2_ldst_pcrel_12
+@ CHECK: ldr.w	lr, _strcmp-4           @ encoding: [0x5f'A',0xf8'A',A,0xe0'A']
+@ CHECK: @   fixup A - offset: 0, value: _strcmp-4, kind: fixup_t2_ldst_pcrel_12
 
 
 @------------------------------------------------------------------------------
@@ -813,7 +816,7 @@ _func:
 @------------------------------------------------------------------------------
         ldrh r5, _bar
 
-@ CHECK: ldrh.w	r5, _bar                @ encoding: [0xbf'A',0xf8'A',A,0x50'A']
+@ CHECK: ldrh.w	r5, _bar                @ encoding: [0x3f'A',0xf8'A',A,0x50'A']
 @ CHECK:     @   fixup A - offset: 0, value: _bar, kind: fixup_t2_ldst_pcrel_12
 
 
@@ -882,7 +885,7 @@ _func:
 @------------------------------------------------------------------------------
         ldrsb r5, _bar
 
-@ CHECK: ldrsb.w r5, _bar               @ encoding: [0x9f'A',0xf9'A',A,0x50'A']
+@ CHECK: ldrsb.w r5, _bar               @ encoding: [0x1f'A',0xf9'A',A,0x50'A']
 @ CHECK:      @   fixup A - offset: 0, value: _bar, kind: fixup_t2_ldst_pcrel_12
 
 
@@ -951,7 +954,7 @@ _func:
 @------------------------------------------------------------------------------
         ldrsh r5, _bar
 
-@ CHECK: ldrsh.w r5, _bar               @ encoding: [0xbf'A',0xf9'A',A,0x50'A']
+@ CHECK: ldrsh.w r5, _bar               @ encoding: [0x3f'A',0xf9'A',A,0x50'A']
 @ CHECK:      @   fixup A - offset: 0, value: _bar, kind: fixup_t2_ldst_pcrel_12
 
 @ TEMPORARILY DISABLED:
@@ -1354,9 +1357,9 @@ _func:
 @------------------------------------------------------------------------------
 @ PLD(literal)
 @------------------------------------------------------------------------------
-        pld  _foo
+@        pld  _foo
 
-@ CHECK: pld	_foo                    @ encoding: [0x9f'A',0xf8'A',A,0xf0'A']
+@ FIXME: pld	_foo                    @ encoding: [0x9f'A',0xf8'A',A,0xf0'A']
             @   fixup A - offset: 0, value: _foo, kind: fixup_t2_ldst_pcrel_12
 
 
@@ -1396,10 +1399,10 @@ _func:
 @------------------------------------------------------------------------------
 @ PLI(literal)
 @------------------------------------------------------------------------------
-        pli  _foo
+@        pli  _foo
 
 
-@ CHECK: pli	_foo                    @ encoding: [0x9f'A',0xf9'A',A,0xf0'A']
+@ FIXME: pli	_foo                    @ encoding: [0x9f'A',0xf9'A',A,0xf0'A']
            @   fixup A - offset: 0, value: _foo, kind: fixup_t2_ldst_pcrel_12