The following patch fixes https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122215
The patch was successfully bootstrapped and tested on x86-64.
commit 6ca1fb648daecaa9c843ff05af304c1fc1a8fcb5 Author: Vladimir N. Makarov <[email protected]> Date: Fri Dec 5 14:21:38 2025 -0500 [PR122215, IRA]: Fix undefined behaviour of improve_allocation Register filters are used in one loop of improve_allocation to ignore some hard regs for cost calculation but it is missed in the subsequent loop using the costs. This results in usage of random (undefined) register costs and in sporadic code generation for riscv32 which uses the filters. gcc/ChangeLog: PR rtl-optimization/122215 * ira-color.cc (improve_allocation): Use register filter for all loop on hard regs. gcc/testsuite/ChangeLog: PR rtl-optimization/122215 * gcc.target/riscv/pr122215.c: New. * lib/target-supports.exp (check_effective_target_valgrind): New. diff --git a/gcc/ira-color.cc b/gcc/ira-color.cc index 4ee2a65e291..a051db27fbf 100644 --- a/gcc/ira-color.cc +++ b/gcc/ira-color.cc @@ -3369,6 +3369,9 @@ improve_allocation (void) for (j = 0; j < class_size; j++) { hregno = ira_class_hard_regs[aclass][j]; + if (NUM_REGISTER_FILTERS + && !test_register_filters (ALLOCNO_REGISTER_FILTERS (a), hregno)) + continue; if (check_hard_reg_p (a, hregno, conflicting_regs, profitable_hard_regs) && min_cost > costs[hregno]) diff --git a/gcc/testsuite/gcc.target/riscv/pr122215.c b/gcc/testsuite/gcc.target/riscv/pr122215.c new file mode 100644 index 00000000000..cdc1ed7c4e7 --- /dev/null +++ b/gcc/testsuite/gcc.target/riscv/pr122215.c @@ -0,0 +1,46 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target valgrind } */ +/* { dg-additional-files "sparseset.supp" } */ +/* { dg-options "-wrapper valgrind,-q,--exit-on-first-error=yes,--error-exitcode=1,--suppressions=${srcdir}/sparseset.supp" } */ + +typedef signed int int32_t; +typedef signed long int int64_t; + +int64_t dual_reg_insn(int64_t x) { + int64_t res; + int64_t zero = 0; + asm ("some_custom_insn %0,%1,%2" : "=R" (res) : "R" (x), "R" (zero)); + return res; +} + +int32_t single_reg_insn(int32_t x) { + int32_t res; + int32_t zero = 0; + asm ("some_custom_insn %0,%1,%2" : "=r" (res) : "r" (x), "r" (zero)); + return res; +} + +int32_t single_reg_insn_explicit_zero(int32_t x) { + int32_t res; + asm ("some_custom_insn %0,%1,%2" : "=r" (res) : "r" (x), "r" (0)); + return res; +} + +int64_t dual_reg_insn2(int64_t x) { + int64_t res; + int64_t zero = 0; + asm ("some_custom_insn %0,%1,%2" : "=R" (res) : "R" (x), "R" (zero)); + return res; + /* This function is IDENTICAL to dual_reg_insn, + * but for some obscure reason (alignment?) + * it decides to use sX registers instead of aX to store zero, + * resulting in a much larger code since it needs to use the stack. + * THIS ONLY HAPPENS SOMETIMES! + */ +} + +int64_t dual_reg_insn_explicit_zero(int64_t x) { + int64_t res; + asm ("some_custom_insn %0,%1,%2" : "=R" (res) : "R" (x), "R" (0LL)); + return res; +} diff --git a/gcc/testsuite/lib/target-supports.exp b/gcc/testsuite/lib/target-supports.exp index 1df80d412da..6251f4e58f8 100644 --- a/gcc/testsuite/lib/target-supports.exp +++ b/gcc/testsuite/lib/target-supports.exp @@ -14762,3 +14762,11 @@ proc check_effective_target_fentry { } { } }] } + +# Check if valgrind executable exists in PATH on host +proc check_effective_target_valgrind { } { + if { [which valgrind] != 0 } { + return 1 + } + return 0 +}
