diff options
| -rw-r--r-- | gcc/gimple-harden-conditionals.cc | 67 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.target/aarch64/pr103149.c | 14 |
2 files changed, 75 insertions, 6 deletions
diff --git a/gcc/gimple-harden-conditionals.cc b/gcc/gimple-harden-conditionals.cc index cfa2361..81867d6 100644 --- a/gcc/gimple-harden-conditionals.cc +++ b/gcc/gimple-harden-conditionals.cc @@ -22,6 +22,8 @@ along with GCC; see the file COPYING3. If not see #include "system.h" #include "coretypes.h" #include "backend.h" +#include "target.h" +#include "rtl.h" #include "tree.h" #include "fold-const.h" #include "gimple.h" @@ -132,25 +134,78 @@ detach_value (location_t loc, gimple_stmt_iterator *gsip, tree val) tree ret = make_ssa_name (TREE_TYPE (val)); SET_SSA_NAME_VAR_OR_IDENTIFIER (ret, SSA_NAME_IDENTIFIER (val)); - /* Output asm ("" : "=g" (ret) : "0" (val)); */ + /* Some modes won't fit in general regs, so we fall back to memory + for them. ??? It would be ideal to try to identify an alternate, + wider or more suitable register class, and use the corresponding + constraint, but there's no logic to go from register class to + constraint, even if there is a corresponding constraint, and even + if we could enumerate constraints, we can't get to their string + either. So this will do for now. */ + bool need_memory = true; + enum machine_mode mode = TYPE_MODE (TREE_TYPE (val)); + if (mode != BLKmode) + for (int i = 0; i < FIRST_PSEUDO_REGISTER; i++) + if (TEST_HARD_REG_BIT (reg_class_contents[GENERAL_REGS], i) + && targetm.hard_regno_mode_ok (i, mode)) + { + need_memory = false; + break; + } + + tree asminput = val; + tree asmoutput = ret; + const char *constraint_out = need_memory ? "=m" : "=g"; + const char *constraint_in = need_memory ? "m" : "0"; + + if (need_memory) + { + tree temp = create_tmp_var (TREE_TYPE (val), "dtch"); + mark_addressable (temp); + + gassign *copyin = gimple_build_assign (temp, asminput); + gimple_set_location (copyin, loc); + gsi_insert_before (gsip, copyin, GSI_SAME_STMT); + + asminput = asmoutput = temp; + } + + /* Output an asm statement with matching input and output. It does + nothing, but after it the compiler no longer knows the output + still holds the same value as the input. */ vec<tree, va_gc> *inputs = NULL; vec<tree, va_gc> *outputs = NULL; vec_safe_push (outputs, build_tree_list (build_tree_list - (NULL_TREE, build_string (2, "=g")), - ret)); + (NULL_TREE, build_string (strlen (constraint_out), + constraint_out)), + asmoutput)); vec_safe_push (inputs, build_tree_list (build_tree_list - (NULL_TREE, build_string (1, "0")), - val)); + (NULL_TREE, build_string (strlen (constraint_in), + constraint_in)), + asminput)); gasm *detach = gimple_build_asm_vec ("", inputs, outputs, NULL, NULL); gimple_set_location (detach, loc); gsi_insert_before (gsip, detach, GSI_SAME_STMT); - SSA_NAME_DEF_STMT (ret) = detach; + if (need_memory) + { + gassign *copyout = gimple_build_assign (ret, asmoutput); + gimple_set_location (copyout, loc); + gsi_insert_before (gsip, copyout, GSI_SAME_STMT); + SSA_NAME_DEF_STMT (ret) = copyout; + + gassign *clobber = gimple_build_assign (asmoutput, + build_clobber + (TREE_TYPE (asmoutput))); + gimple_set_location (clobber, loc); + gsi_insert_before (gsip, clobber, GSI_SAME_STMT); + } + else + SSA_NAME_DEF_STMT (ret) = detach; return ret; } diff --git a/gcc/testsuite/gcc.target/aarch64/pr103149.c b/gcc/testsuite/gcc.target/aarch64/pr103149.c new file mode 100644 index 0000000..906bc9a --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/pr103149.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-march=armv8-a+sve -O2 -fharden-conditional-branches -fno-tree-scev-cprop" } */ + +/* -fharden-conditional-branches prevents optimization of its redundant + compares by detaching values from the operands with asm statements. They + used to require GENERAL_REGS, but the vectorized booleans, generated while + vectorizing this function, can't be held in GENERAL_REGS. */ + +void +foo (int *p) +{ + while (*p < 1) + ++*p; +} |