The following enhances chrec_fold_plus_1 to handle a case to avoid ICEing during GRAPHITE code-gen. It teaches us to handle (signed T) { (T) x, +, y } + (signed T) z as (signed T) ( { (T) x, +, y } + (T) (singed T) z ) instead of failing with chrec_not_known.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk. Richard. 2018-01-24 Richard Biener <rguent...@suse.de> PR tree-optimization/83176 * tree-chrec.c (chrec_fold_plus_1): Handle (signed T){(T) .. } operands. * gcc.dg/graphite/pr83176.c: New testcase. Index: gcc/tree-chrec.c =================================================================== --- gcc/tree-chrec.c (revision 256977) +++ gcc/tree-chrec.c (working copy) @@ -295,8 +295,23 @@ chrec_fold_plus_1 (enum tree_code code, return chrec_fold_plus_poly_poly (code, type, op0, op1); CASE_CONVERT: - if (tree_contains_chrecs (op1, NULL)) - return chrec_dont_know; + { + /* We can strip sign-conversions to signed by performing the + operation in unsigned. */ + tree optype = TREE_TYPE (TREE_OPERAND (op1, 0)); + if (INTEGRAL_TYPE_P (type) + && INTEGRAL_TYPE_P (optype) + && tree_nop_conversion_p (type, optype) + && TYPE_UNSIGNED (optype)) + return chrec_convert (type, + chrec_fold_plus_1 (code, optype, + chrec_convert (optype, + op0, NULL), + TREE_OPERAND (op1, 0)), + NULL); + if (tree_contains_chrecs (op1, NULL)) + return chrec_dont_know; + } /* FALLTHRU */ default: @@ -313,8 +328,23 @@ chrec_fold_plus_1 (enum tree_code code, } CASE_CONVERT: - if (tree_contains_chrecs (op0, NULL)) - return chrec_dont_know; + { + /* We can strip sign-conversions to signed by performing the + operation in unsigned. */ + tree optype = TREE_TYPE (TREE_OPERAND (op0, 0)); + if (INTEGRAL_TYPE_P (type) + && INTEGRAL_TYPE_P (optype) + && tree_nop_conversion_p (type, optype) + && TYPE_UNSIGNED (optype)) + return chrec_convert (type, + chrec_fold_plus_1 (code, optype, + TREE_OPERAND (op0, 0), + chrec_convert (optype, + op1, NULL)), + NULL); + if (tree_contains_chrecs (op0, NULL)) + return chrec_dont_know; + } /* FALLTHRU */ default: Index: gcc/testsuite/gcc.dg/graphite/pr83176.c =================================================================== --- gcc/testsuite/gcc.dg/graphite/pr83176.c (nonexistent) +++ gcc/testsuite/gcc.dg/graphite/pr83176.c (working copy) @@ -0,0 +1,42 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -floop-nest-optimize" } */ + +int wx, qi; + +void +yj (int gw) +{ + int *ak = &gw; + + while (wx != 0) + { + int k2 = (__INTPTR_TYPE__)&ak; + int **xq = (int **)&k2; + +ja: + *xq = &gw; + + while (qi < 1) + { + unsigned short int ey; + +be: + for (ey = 0; ey < 251; ++ey) + { + for (wx = 0; wx < 2; ++wx) + { + } + + *ak += 8555712; + k2 += *ak; + } + ++qi; + } + } + + gw = 1; + if (gw != 0) + goto ja; + else + goto be; +}