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Commit Graph

Author	SHA1	Message	Date
Florian Hahn	30932a3c16	[InstSimplify] More fcmp cases when comparing against negative constants. Summary: For known positive non-zero value X: fcmp uge X, -C => true fcmp ugt X, -C => true fcmp une X, -C => true fcmp oeq X, -C => false fcmp ole X, -C => false fcmp olt X, -C => false Patch by Paul Walker. Reviewers: majnemer, t.p.northover, spatel, RKSimon Reviewed By: spatel Subscribers: fhahn, llvm-commits Differential Revision: https://reviews.llvm.org/D40012 llvm-svn: 319538	2017-12-01 12:34:16 +00:00
Arch D. Robison	8ed0854f55	Broaden optimization of fcmp ([us]itofp x, constant) by instcombine. The patch extends the optimization to cases where the constant's magnitude is so small or large that the rounding of the conversion is irrelevant. The "so small" case includes negative zero. Differential review: http://reviews.llvm.org/D11210 llvm-svn: 247708	2015-09-15 17:51:59 +00:00
Matt Arsenault	55e7312cd8	Convert fcmp with 0.0 from casted integers to icmp This is already handled in general when it is known the conversion can't lose bits with smaller integer types casted into wider floating point types. This pattern happens somewhat often in GPU programs that cast workitem intrinsics to float, which are often compared with 0. Specifically handle the special case of compares with zero which should also be known to not lose information. I had a more general version of this which allows equality compares if the casted float is exactly representable in the integer, but I'm not 100% confident that is always correct. Also fold cases that aren't integers to true / false. llvm-svn: 225265	2015-01-06 15:50:59 +00:00

Author

SHA1

Message

Date

Florian Hahn

30932a3c16

[InstSimplify] More fcmp cases when comparing against negative constants.

Summary:
For known positive non-zero value X:
    fcmp uge X, -C => true
    fcmp ugt X, -C => true
    fcmp une X, -C => true
    fcmp oeq X, -C => false
    fcmp ole X, -C => false
    fcmp olt X, -C => false


Patch by Paul Walker.

Reviewers: majnemer, t.p.northover, spatel, RKSimon

Reviewed By: spatel

Subscribers: fhahn, llvm-commits

Differential Revision: https://reviews.llvm.org/D40012

llvm-svn: 319538

2017-12-01 12:34:16 +00:00

Arch D. Robison

8ed0854f55

Broaden optimization of fcmp ([us]itofp x, constant) by instcombine.

The patch extends the optimization to cases where the constant's
magnitude is so small or large that the rounding of the conversion
is irrelevant.  The "so small" case includes negative zero.

Differential review: http://reviews.llvm.org/D11210

llvm-svn: 247708

2015-09-15 17:51:59 +00:00

Matt Arsenault

55e7312cd8

Convert fcmp with 0.0 from casted integers to icmp

This is already handled in general when it is known the
conversion can't lose bits with smaller integer types
casted into wider floating point types.

This pattern happens somewhat often in GPU programs that cast
workitem intrinsics to float, which are often compared with 0.

Specifically handle the special case of compares with zero which
should also be known to not lose information. I had a more general
version of this which allows equality compares if the casted float is
exactly representable in the integer, but I'm not 100% confident that
is always correct.

Also fold cases that aren't integers to true / false.

llvm-svn: 225265

2015-01-06 15:50:59 +00:00

3 Commits