- this expression is explicitly marked no-signed-zero, or
- no-signed-zero of this expression can be derived from some context.
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o. X/C1 * C2 => X * (C2/C1) (if C2/C1 is neither special FP nor denormal)
o. X/C1 * C2 -> X/(C1/C2) (if C2/C1 is either specical FP or denormal, but C1/C2 is a normal Fp)
Let MDC denote multiplication or dividion with one & only one operand being a constant
o. (MDC ± C1) * C2 => (MDC * C2) ± (C1 * C2)
(so long as the constant-folding doesn't yield any denormal or special value)
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turning a code like this:
if (foo)
free(foo)
into that:
free(foo)
Move a call to free from basic block FB into FB's predecessor, P,
when the path from P to FB is taken only if the argument of free is
not equal to NULL.
Some restrictions apply on P and FB to be sure that this code motion
is profitable. Namely:
1. FB must have only one predecessor P.
2. FB must contain only the call to free plus an unconditional
branch to S.
3. P's successors are FB and S.
Because of 1., we will not increase the code size when moving the call
to free from FB to P.
Because of 2., FB will be empty after the move.
Because of 2. and 3., P's branch instruction becomes useless, so as FB
(simplifycfg will do the job).
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into their new header subdirectory: include/llvm/IR. This matches the
directory structure of lib, and begins to correct a long standing point
of file layout clutter in LLVM.
There are still more header files to move here, but I wanted to handle
them in separate commits to make tracking what files make sense at each
layer easier.
The only really questionable files here are the target intrinsic
tablegen files. But that's a battle I'd rather not fight today.
I've updated both CMake and Makefile build systems (I think, and my
tests think, but I may have missed something).
I've also re-sorted the includes throughout the project. I'll be
committing updates to Clang, DragonEgg, and Polly momentarily.
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The later API is nicer than the former, and is correct regarding wrap-around offsets (if anyone cares).
There are a few more places left with duplicated code, which I'll remove soon.
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such as by a compiler warning, a check in clang -fsanitizer=undefined, being
optimized to unreachable, or a combination of the above. PR14722.
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When the backend is used from clang, it should produce proper diagnostics
instead of just printing messages to errs(). Other clients may also want to
register their own error handlers with the LLVMContext, and the same handler
should work for warnings in the same way as the existing emitError methods.
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When the least bit of C is greater than V, (x&C) must be greater than V
if it is not zero, so the comparison can be simplified.
Although this was suggested in Target/X86/README.txt, it benefits any
architecture with a directly testable form of AND.
Patch by Kevin Schoedel
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This assumes (1 << n) is always not zero. Consider n is greater than word size.
Although I know it is undefined, this transforms undefined behavior hidden.
This led clang unexpected behavior with some failures. I will investigate to fix undefined shl in clang.
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In a previous thread it was pointed out that isPowerOfTwo is not a very precise
name since it can return false for powers of two if it is unable to show that
they are powers of two.
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Provides m_Argument that allows matching against a CallSite's specified argument. Provides m_Intrinsic pattern that can be templatized over the intrinsic id and bind/match arguments similarly to other pattern matchers. Implementations provided for 0 to 4 arguments, though it's very simple to extend for more. Also provides example template specialization for bswap (m_BSwap) and example of code cleanup for its use.
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been used in the first place. It simply was passed to the function and to the
recursive invocations. Simply drop the parameter and update the callers for the
new signature.
Patch by Saleem Abdulrasool!
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This change attempts to simplify (X^Y) -> X or Y in the user's context if we know that
only bits from X or Y are demanded.
A minimized case is provided bellow. This change will simplify "t>>16" into "var1 >>16".
=============================================================
unsigned foo (unsigned val1, unsigned val2) {
unsigned t = val1 ^ 1234;
return (t >> 16) | t; // NOTE: t is used more than once.
}
=============================================================
Note that if the "t" were used only once, the expression would be finally optimized as well.
However, with with this change, the optimization will take place earlier.
Reviewed by Nadav, Thanks a lot!
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missed in the first pass because the script didn't yet handle include
guards.
Note that the script is now able to handle all of these headers without
manual edits. =]
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The type of shirt-right (logical or arithemetic) should remain unchanged
when transforming "X << C1 >> C2" into "X << (C1-C2)"
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Sooooo many of these had incorrect or strange main module includes.
I have manually inspected all of these, and fixed the main module
include to be the nearest plausible thing I could find. If you own or
care about any of these source files, I encourage you to take some time
and check that these edits were sensible. I can't have broken anything
(I strictly added headers, and reordered them, never removed), but they
may not be the headers you'd really like to identify as containing the
API being implemented.
Many forward declarations and missing includes were added to a header
files to allow them to parse cleanly when included first. The main
module rule does in fact have its merits. =]
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The simplify-libcalls pass maintained a statistic to count the number
of library calls that have been simplified. Now that library call
simplification is being carried out in instcombine the statistic should
be moved to there.
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