From 065433b4ce8d9676ba3be4871c520b8257f21c14 Mon Sep 17 00:00:00 2001 From: Jeff Law Date: Tue, 19 Nov 2024 19:24:41 -0700 Subject: [RISC-V][PR target/117649] Fix branch on masked values splitter Andreas reported GCC mis-compiled GAS for risc-v Thankfully he also reduced it to a nice little testcase. So the whole point of the pattern in question is to "reduce" the constants by right shifting away common unnecessary bits in RTL expressions like this: > [(set (pc) > (if_then_else (any_eq > (and:ANYI (match_operand:ANYI 1 "register_operand" "r") > (match_operand 2 "shifted_const_arith_operand" "i")) > (match_operand 3 "shifted_const_arith_operand" "i")) > (label_ref (match_operand 0 "" "")) > (pc))) When applicable, the reduced constants in operands 2/3 fit into a simm12 and thus do not need multi-instruction synthesis. Note that we have to also shift operand 1. That shift should have been an arithmetic shift, but was incorrectly coded as a logical shift. Fixed with the obvious change on the right shift opcode. Expecting to push to the trunk once the pre-commit tester renders its verdict. I've already tested in this my tester for rv32 and rv64. PR target/117649 gcc/ * config/riscv/riscv.md (branch on masked/shifted operands): Use arithmetic rather than logical shift for operand 1. gcc/testsuite * gcc.target/riscv/branch-1.c: Update expected output. * gcc.target/riscv/pr117649.c: New test. --- gcc/config/riscv/riscv.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'gcc/config/riscv/riscv.md') diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md index 5b7b735..eb5cd6f 100644 --- a/gcc/config/riscv/riscv.md +++ b/gcc/config/riscv/riscv.md @@ -3153,7 +3153,7 @@ INTVAL (operands[3]))" "#" "&& reload_completed" - [(set (match_dup 4) (lshiftrt:X (match_dup 1) (match_dup 7))) + [(set (match_dup 4) (ashiftrt:X (match_dup 1) (match_dup 7))) (set (match_dup 4) (and:X (match_dup 4) (match_dup 8))) (set (match_dup 5) (match_dup 9)) (set (pc) (if_then_else (any_eq (match_dup 4) (match_dup 5)) -- cgit v1.1