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
--- a/lib/Target/ARM/ARMAddressingModes.h
+++ b/lib/Target/ARM/ARMAddressingModes.h
@@ -151,22 +151,13 @@
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 @@
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) {