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author | Andrew Trick <atrick@apple.com> | 2012-08-29 03:52:57 +0000 |
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committer | Andrew Trick <atrick@apple.com> | 2012-08-29 03:52:57 +0000 |
commit | 2b70dfaaebcc436c53b2c86cd8a9574baba47253 (patch) | |
tree | c21e370e68a8e470f301212fd22f1b7fceb99ddb /utils | |
parent | c4dc2490c4ea2c75e451eec5950179f06d2610a2 (diff) | |
download | llvm-2b70dfaaebcc436c53b2c86cd8a9574baba47253.tar.gz llvm-2b70dfaaebcc436c53b2c86cd8a9574baba47253.tar.bz2 llvm-2b70dfaaebcc436c53b2c86cd8a9574baba47253.tar.xz |
Fix a nondeterminism in the ARM assembler.
Adding arbitrary records to ARM.td would break
basic-arm-instructions.s because selection of nop vs mov r0,r0 was
ambiguous (this will be tested by a subsequent addition to ARM.td).
An imperfect but sensible fix is to give precedence to match rules
that have more constraints.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162824 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'utils')
-rw-r--r-- | utils/TableGen/AsmMatcherEmitter.cpp | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/utils/TableGen/AsmMatcherEmitter.cpp b/utils/TableGen/AsmMatcherEmitter.cpp index 097cbfc680..9e8e9462cc 100644 --- a/utils/TableGen/AsmMatcherEmitter.cpp +++ b/utils/TableGen/AsmMatcherEmitter.cpp @@ -488,6 +488,15 @@ struct MatchableInfo { return false; } + // Give matches that require more features higher precedence. This is useful + // because we cannot define AssemblerPredicates with the negation of + // processor features. For example, ARM v6 "nop" may be either a HINT or + // MOV. With v6, we want to match HINT. The assembler has no way to + // predicate MOV under "NoV6", but HINT will always match first because it + // requires V6 while MOV does not. + if (RequiredFeatures.size() != RHS.RequiredFeatures.size()) + return RequiredFeatures.size() > RHS.RequiredFeatures.size(); + return false; } |