record delinearization result and reuse it in polyhedral translation

record delinearization result and reuse it in polyhedral translation

Without this patch, the testcase would fail on the delinearization of the second
array:

; void foo(long n, long m, long o, double A[n][m][o]) {
;   for (long i = 0; i < n; i++)
;     for (long j = 0; j < m; j++)
;       for (long k = 0; k < o; k++) {
;         A[i+3][j-4][k+7] = 1.0;
;         A[i][0][k] = 2.0;
;       }
; }

; CHECK: [n, m, o] -> { Stmt_for_body6[i0, i1, i2] -> MemRef_A[3 + i0, -4 + i1, 7 + i2] };
; CHECK: [n, m, o] -> { Stmt_for_body6[i0, i1, i2] -> MemRef_A[i0, 0, i2] };

Here is the output of FileCheck on the testcase without this patch:

; CHECK: [n, m, o] -> { Stmt_for_body6[i0, i1, i2] -> MemRef_A[i0, 0, i2] };
         ^
<stdin>:26:2: note: possible intended match here
 [n, m, o] -> { Stmt_for_body6[i0, i1, i2] -> MemRef_A[o0] };
 ^

It is possible to find a good delinearization for A[i][0][k] only in the context
of the delinearization of both array accesses.

There are two ways to delinearize together all array subscripts touching the
same base address: either duplicate the code from scop detection to first gather
all array references and then run the delinearization; or as implemented in this
patch, use the same delinearization info that we computed during scop detection.

llvm-svn: 210117