mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-01-15 07:34:33 +00:00
029a76b0a2
'OK_NonUniformConstValue' to identify operands which are constants but not constant splats. The cost model now allows returning 'OK_NonUniformConstValue' for non splat operands that are instances of ConstantVector or ConstantDataVector. With this change, targets are now able to compute different costs for instructions with non-uniform constant operands. For example, On X86 the cost of a vector shift may vary depending on whether the second operand is a uniform or non-uniform constant. This patch applies the following changes: - The cost model computation now takes into account non-uniform constants; - The cost of vector shift instructions has been improved in X86TargetTransformInfo analysis pass; - BBVectorize, SLPVectorizer and LoopVectorize now know how to distinguish between non-uniform and uniform constant operands. Added a new test to verify that the output of opt '-cost-model -analyze' is valid in the following configurations: SSE2, SSE4.1, AVX, AVX2. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201272 91177308-0d34-0410-b5e6-96231b3b80d8
Analysis Opportunities:
//===---------------------------------------------------------------------===//
In test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll, the
ScalarEvolution expression for %r is this:
{1,+,3,+,2}<loop>
Outside the loop, this could be evaluated simply as (%n * %n), however
ScalarEvolution currently evaluates it as
(-2 + (2 * (trunc i65 (((zext i64 (-2 + %n) to i65) * (zext i64 (-1 + %n) to i65)) /u 2) to i64)) + (3 * %n))
In addition to being much more complicated, it involves i65 arithmetic,
which is very inefficient when expanded into code.
//===---------------------------------------------------------------------===//
In formatValue in test/CodeGen/X86/lsr-delayed-fold.ll,
ScalarEvolution is forming this expression:
((trunc i64 (-1 * %arg5) to i32) + (trunc i64 %arg5 to i32) + (-1 * (trunc i64 undef to i32)))
This could be folded to
(-1 * (trunc i64 undef to i32))
//===---------------------------------------------------------------------===//