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| author | Daniel Berlin <dberlin@dberlin.org> | 2004-11-03 17:32:34 +0000 |
|---|---|---|
| committer | Daniel Berlin <dberlin@gcc.gnu.org> | 2004-11-03 17:32:34 +0000 |
| commit | c4bda9f0cf757474d9970e3e9174a76eb31b0444 (patch) | |
| tree | 8465e9dd44bb38c923701c2c41d78e75fb2c644d /gcc/lambda-code.c | |
| parent | 308d51892fb3d625bbaa1b458a52d72527fd92cc (diff) | |
| download | gcc-c4bda9f0cf757474d9970e3e9174a76eb31b0444.zip gcc-c4bda9f0cf757474d9970e3e9174a76eb31b0444.tar.gz gcc-c4bda9f0cf757474d9970e3e9174a76eb31b0444.tar.bz2 | |
lambda-code.c (lambda_compute_auxillary_space): Update comments.
2004-11-02 Daniel Berlin <dberlin@dberlin.org>
* lambda-code.c (lambda_compute_auxillary_space): Update comments.
(lambda_compute_target_space). Ditto.
* lambda.h (lambda_trans_matrix): Ditto.
(lambda_linear_expression): Ditto.
(lambda_body_vector): Ditto.
(lambda_loopnest): Ditto.
* tree-loop-linear.c (gather_interchange_stats): Combine tests,
update comments, and remove pointless addition of 0.
(linear_transform_loops): Update comments.
From-SVN: r90029
Diffstat (limited to 'gcc/lambda-code.c')
| -rw-r--r-- | gcc/lambda-code.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/gcc/lambda-code.c b/gcc/lambda-code.c index d564f43..0d066b9 100644 --- a/gcc/lambda-code.c +++ b/gcc/lambda-code.c @@ -651,7 +651,19 @@ compute_nest_using_fourier_motzkin (int size, } /* Compute the loop bounds for the auxiliary space NEST. - Input system used is Ax <= b. TRANS is the unimodular transformation. */ + Input system used is Ax <= b. TRANS is the unimodular transformation. + Given the original nest, this function will + 1. Convert the nest into matrix form, which consists of a matrix for the + coefficients, a matrix for the + invariant coefficients, and a vector for the constants. + 2. Use the matrix form to calculate the lattice base for the nest (which is + a dense space) + 3. Compose the dense space transform with the user specified transform, to + get a transform we can easily calculate transformed bounds for. + 4. Multiply the composed transformation matrix times the matrix form of the + loop. + 5. Transform the newly created matrix (from step 4) back into a loop nest + using fourier motzkin elimination to figure out the bounds. */ static lambda_loopnest lambda_compute_auxillary_space (lambda_loopnest nest, @@ -786,9 +798,11 @@ lambda_compute_auxillary_space (lambda_loopnest nest, } /* Compute the loop bounds for the target space, using the bounds of - the auxiliary nest AUXILLARY_NEST, and the triangular matrix H. This is - done by matrix multiplication and then transformation of the new matrix - back into linear expression form. + the auxiliary nest AUXILLARY_NEST, and the triangular matrix H. + The target space loop bounds are computed by multiplying the triangular + matrix H by the auxillary nest, to get the new loop bounds. The sign of + the loop steps (positive or negative) is then used to swap the bounds if + the loop counts downwards. Return the target loopnest. */ static lambda_loopnest |