From 8df8eb6dd5b02d2a5b950a00c09590da423db8cc Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Thu, 6 Jan 2022 09:29:34 +0100 Subject: [PATCH] ifcvt: Check for asm goto at the end of then_bb/else_bb in ifcvt [PR103908] On the following testcase, RTL ifcvt sees then_bb (note 7 6 8 3 [bb 3] NOTE_INSN_BASIC_BLOCK) (insn 8 7 9 3 (set (mem/c:SI (symbol_ref:DI ("b") [flags 0x2] ) [1 b+0 S4 A32]) (const_int 1 [0x1])) "pr103908.c":6:7 81 {*movsi_internal} (nil)) (jump_insn 9 8 13 3 (parallel [ (asm_operands/v ("# insn 1") ("") 0 [] [] [ (label_ref:DI 21) ] pr103908.c:7) (clobber (reg:CC 17 flags)) ]) "pr103908.c":7:5 -1 (expr_list:REG_UNUSED (reg:CC 17 flags) (nil)) -> 21) and similarly else_bb (just with a different asm_operands template). It checks that those basic blocks have a single successor and uses last_active_insn which intentionally skips over JUMP_INSNs, sees both basic blocks contain the same set and merges them (or if the sets are different, attempts some other noce optimization). But we can't assume that the jump, even when it has only a single successor, has no side-effects. The following patch fixes it by punting if test_bb ends with a JUMP_INSN that isn't onlyjump_p. 2022-01-06 Jakub Jelinek PR rtl-optimization/103908 * ifcvt.c (bb_valid_for_noce_process_p): Punt on bbs ending with asm goto. * gcc.target/i386/pr103908.c: New test. (cherry picked from commit 80ad67e2af0620d58d57d0406dc22693cf5b8ca9) --- gcc/ifcvt.c | 6 ++++++ gcc/testsuite/gcc.target/i386/pr103908.c | 24 ++++++++++++++++++++++++ 2 files changed, 30 insertions(+) create mode 100644 gcc/testsuite/gcc.target/i386/pr103908.c diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c index 977dd1bd403a..4baf07a7e97a 100644 --- a/gcc/ifcvt.c +++ b/gcc/ifcvt.c @@ -3064,6 +3064,12 @@ bb_valid_for_noce_process_p (basic_block test_bb, rtx cond, if (!insn_valid_noce_process_p (last_insn, cc)) return false; + + /* Punt on blocks ending with asm goto or jumps with other side-effects, + last_active_insn ignores JUMP_INSNs. */ + if (JUMP_P (BB_END (test_bb)) && !onlyjump_p (BB_END (test_bb))) + return false; + last_set = single_set (last_insn); rtx x = SET_DEST (last_set); diff --git a/gcc/testsuite/gcc.target/i386/pr103908.c b/gcc/testsuite/gcc.target/i386/pr103908.c new file mode 100644 index 000000000000..7c57e1ddf6af --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr103908.c @@ -0,0 +1,24 @@ +/* PR rtl-optimization/103908 */ +/* { dg-do compile } */ +/* { dg-options "-O1 -fdisable-tree-cselim -fno-tree-sink" } */ +/* { dg-final { scan-assembler "# insn 1" } } */ +/* { dg-final { scan-assembler "# insn 2" } } */ + +int a, b; + +void +foo (void) +{ + if (a) + { + b = 1; + asm goto ("# insn 1" : : : : lab1); + lab1:; + } + else + { + b = 1; + asm goto ("# insn 2" : : : : lab2); + lab2:; + } +} -- 2.47.2