Fix Thumb2 aliasing complementary instructions taking modified immediates

There are many Thumb instructions which take 12-bit immediates encoded in a special
8-byte value + 4-byte rotator form. Not all numbers are represented, and it's legal
to transform an assembly instruction to be able to encode the immediate.

For example: AND and BIC are complementary instructions; one can switch the AND
to a BIC as long as the immediate is complemented. 

The intent is to switch one instruction into its complementary one when the immediate
cannot be encoded in the form requested in the original assembly and when the 
complementary immediate is encodable.

The patch addresses two issues:
1. definition of t2SOImmNot immediate - it has to check that the orignal value is
not encoded naturally
2. t2AND and t2BIC instruction aliases which should use the Thumb2 SOImm operand 
rather than the ARM one.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188548 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 6 insertions, 5 deletions

diff --git a/lib/Target/ARM/ARMInstrThumb2.td b/lib/Target/ARM/ARMInstrThumb2.td
index 77a3759..376246b 100644
--- a/lib/Target/ARM/ARMInstrThumb2.td
+++ b/lib/Target/ARM/ARMInstrThumb2.td
@@ -4353,16 +4353,16 @@ def : t2InstAlias<"mvn${p} $Rd, $imm",
                   (t2MOVi rGPR:$Rd, t2_so_imm_not:$imm, pred:$p, zero_reg)>;
 // Same for AND <--> BIC
 def : t2InstAlias<"bic${s}${p} $Rd, $Rn, $imm",
-                  (t2ANDri rGPR:$Rd, rGPR:$Rn, so_imm_not:$imm,
+                  (t2ANDri rGPR:$Rd, rGPR:$Rn, t2_so_imm_not:$imm,
                            pred:$p, cc_out:$s)>;
 def : t2InstAlias<"bic${s}${p} $Rdn, $imm",
-                  (t2ANDri rGPR:$Rdn, rGPR:$Rdn, so_imm_not:$imm,
+                  (t2ANDri rGPR:$Rdn, rGPR:$Rdn, t2_so_imm_not:$imm,
                            pred:$p, cc_out:$s)>;
 def : t2InstAlias<"and${s}${p} $Rd, $Rn, $imm",
-                  (t2BICri rGPR:$Rd, rGPR:$Rn, so_imm_not:$imm,
+                  (t2BICri rGPR:$Rd, rGPR:$Rn, t2_so_imm_not:$imm,
                            pred:$p, cc_out:$s)>;
 def : t2InstAlias<"and${s}${p} $Rdn, $imm",
-                  (t2BICri rGPR:$Rdn, rGPR:$Rdn, so_imm_not:$imm,
+                  (t2BICri rGPR:$Rdn, rGPR:$Rdn, t2_so_imm_not:$imm,
                            pred:$p, cc_out:$s)>;
 // Likewise, "add Rd, t2_so_imm_neg" -> sub
 def : t2InstAlias<"add${s}${p} $Rd, $Rn, $imm",
diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index 3d7baf5..d48ece1 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -946,7 +946,8 @@ public:
     const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(getImm());
     if (!CE) return false;
     int64_t Value = CE->getValue();
-    return ARM_AM::getT2SOImmVal(~Value) != -1;
+    return ARM_AM::getT2SOImmVal(Value) == -1 &&
+      ARM_AM::getT2SOImmVal(~Value) != -1;
   }
   bool isT2SOImmNeg() const {
     if (!isImm()) return false;