Replace r101053 with a fix for getSOImmValRotate() so that it will correctly

recognize all the valid rotated immediates.  This fixes the disassembler
issue and will also help codegen for some unusual constant values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101114 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMAddressingModes.h b/lib/Target/ARM/ARMAddressingModes.h
index 45b37b1..f414744 100644 (file)
--- a/lib/Target/ARM/ARMAddressingModes.h
+++ b/lib/Target/ARM/ARMAddressingModes.h
@@ -151,22 +151,13 @@ namespace ARM_AM {
     if ((rotr32(Imm, RotAmt) & ~255U) == 0)
       return (32-RotAmt)&31;  // HW rotates right, not left.
 
-    // For values like 0xF000000F, we should skip the first run of ones, then
+    // For values like 0xF000000F, we should ignore the low 7 bits, then
     // retry the hunt.
-    if (Imm & 1) {
-      unsigned TrailingOnes = CountTrailingZeros_32(~Imm);
-      if (TrailingOnes != 32) {  // Avoid overflow on 0xFFFFFFFF
-        // Restart the search for a high-order bit after the initial seconds of
-        // ones.
-        unsigned TZ2 = CountTrailingZeros_32(Imm & ~((1 << TrailingOnes)-1));
-
-        // Rotate amount must be even.
-        unsigned RotAmt2 = TZ2 & ~1;
-
-        // If this fits, use it.
-        if (RotAmt2 != 32 && (rotr32(Imm, RotAmt2) & ~255U) == 0)
-          return (32-RotAmt2)&31;  // HW rotates right, not left.
-      }
+    if (Imm & 127U) {
+      unsigned TZ2 = CountTrailingZeros_32(Imm & ~127U);
+      unsigned RotAmt2 = TZ2 & ~1;
+      if ((rotr32(Imm, RotAmt2) & ~255U) == 0)
+        return (32-RotAmt2)&31;  // HW rotates right, not left.
     }
 
     // Otherwise, we have no way to cover this span of bits with a single
@@ -193,43 +184,6 @@ namespace ARM_AM {
     return rotl32(Arg, RotAmt) | ((RotAmt>>1) << 8);
   }
 
-  /// getSOImmValOneRotate - Try to handle Imm with an immediate shifter
-  /// operand, computing the rotate amount to use.  If this immediate value
-  /// cannot be handled with a single shifter-op, return 0.
-  static unsigned getSOImmValOneRotate(unsigned Imm) {
-    // A5.2.4 Constants with multiple encodings
-    // The lowest unsigned value of rotation wins!
-    for (unsigned R = 1; R <= 15; ++R)
-      if ((Imm & rotr32(~255U, 2*R)) == 0)
-        return 2*R;
-
-    // Failed to find a suitable rotate amount.
-    return 0;
-  }
-
-  /// getSOImmValOneOrNoRotate - Given a 32-bit immediate, if it is something
-  /// that can fit into a shifter_operand immediate operand, return the 12-bit
-  /// encoding for it.  If not, return -1.  This is different from getSOImmVal()
-  /// in that getSOImmVal() is used during codegen, for example,
-  /// rewriteARMFrameIndex() where return value of -1 is not considered fatal.
-  ///
-  /// The current consumer of this API is printSOImm() within ARMInstPrinter.cpp
-  /// where return value of -1 indicates that the Arg is not a valid so_imm val!
-  static inline int getSOImmValOneOrNoRotate(unsigned Arg) {
-    // 8-bit (or less) immediates are trivially shifter_operands with a rotate
-    // of zero.
-    if ((Arg & ~255U) == 0) return Arg;
-
-    unsigned RotAmt = getSOImmValOneRotate(Arg);
-
-    // If this cannot be handled with a single shifter_op, bail out.
-    if (rotr32(~255U, RotAmt) & Arg)
-      return -1;
-
-    // Encode this correctly.
-    return rotl32(Arg, RotAmt) | ((RotAmt>>1) << 8);
-  }
-
   /// isSOImmTwoPartVal - Return true if the specified value can be obtained by
   /// or'ing together two SOImmVal's.
   static inline bool isSOImmTwoPartVal(unsigned V) {

diff --git a/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp b/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp
index c73fa13..ef5ead6 100644 (file)
--- a/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp
+++ b/lib/Target/ARM/AsmPrinter/ARMInstPrinter.cpp
@@ -225,7 +225,7 @@ void ARMInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
 static void printSOImm(raw_ostream &O, int64_t V, bool VerboseAsm,
                        const MCAsmInfo *MAI) {
   // Break it up into two parts that make up a shifter immediate.
-  V = ARM_AM::getSOImmValOneOrNoRotate(V);
+  V = ARM_AM::getSOImmVal(V);
   assert(V != -1 && "Not a valid so_imm value!");
   
   unsigned Imm = ARM_AM::getSOImmValImm(V);