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authorDavid Goodwin <david_goodwin@apple.com>2009-07-14 00:57:56 +0000
committerDavid Goodwin <david_goodwin@apple.com>2009-07-14 00:57:56 +0000
commitf354d36027f21554f43b365cd07cf965a7687096 (patch)
tree2f3e9b83a10b99dca3a332a9ff4f0c5d62cc772a /lib
parentbd760a50153e3f543e5ccf0d5d6a34e3a33bd88e (diff)
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Fix detection of valid BFC immediates.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75576 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r--lib/Target/ARM/ARMInstrInfo.td20
1 files changed, 10 insertions, 10 deletions
diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index b3a52d6..17e7365 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -168,16 +168,16 @@ def bf_inv_mask_imm : Operand<i32>,
uint32_t v = (uint32_t)N->getZExtValue();
if (v == 0xffffffff)
return 0;
- // naive checker. should do better, but simple is best for now since it's
- // more likely to be correct.
- while (v & 1) v >>= 1; // shift off the leading 1's
- if (v)
- {
- while (!(v & 1)) v >>=1; // shift off the mask
- while (v & 1) v >>= 1; // shift off the trailing 1's
- }
- // if this is a mask for clearing a bitfield, what's left should be zero.
- return (v == 0);
+ // there can be 1's on either or both "outsides", all the "inside"
+ // bits must be 0's
+ unsigned int lsb = 0, msb = 31;
+ while (v & (1 << msb)) --msb;
+ while (v & (1 << lsb)) ++lsb;
+ for (unsigned int i = lsb; i <= msb; ++i) {
+ if (v & (1 << i))
+ return 0;
+ }
+ return 1;
}] > {
let PrintMethod = "printBitfieldInvMaskImmOperand";
}