From c6dc3dd72b747a057770087998a1f9ef0b3f1882 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Date: Fri, 20 Feb 2015 17:06:16 +0100 Subject: [PATCH] milkymist-pfpu: fix GCC 5.0.0 aggressive-loop-optimizations warning MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit man gcc: Warn if in a loop with constant number of iterations the compiler detects undefined behavior in some statement during one or more of the iterations. Milkymist pfpu has no jump instructions, so checking for MICROCODE_WORDS instructions should have kept us in bounds of s->microcode, but i++ allowed one loop too many, hw/misc/milkymist-pfpu.c: In function ‘pfpu_write’: hw/misc/milkymist-pfpu.c:365:20: error: loop exit may only be reached after undefined behavior [-Werror=aggressive-loop-optimizations] if (i++ >= MICROCODE_WORDS) { ^ hw/misc/milkymist-pfpu.c:167:14: note: possible undefined statement is here uint32_t insn = s->microcode[pc]; ^ The code can still access out of bounds, because it presumes that PC register always begins at 0, and we allow writing to it. Signed-off-by: Radim Krčmář Acked-by: Michael Walle Signed-off-by: Michael Tokarev --- hw/misc/milkymist-pfpu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/misc/milkymist-pfpu.c b/hw/misc/milkymist-pfpu.c index 609f33f..08b604f 100644 --- a/hw/misc/milkymist-pfpu.c +++ b/hw/misc/milkymist-pfpu.c @@ -362,7 +362,7 @@ static void pfpu_start(MilkymistPFPUState *s) i = 0; while (pfpu_decode_insn(s)) { /* decode at most MICROCODE_WORDS instructions */ - if (i++ >= MICROCODE_WORDS) { + if (++i >= MICROCODE_WORDS) { error_report("milkymist_pfpu: too many instructions " "executed in microcode. No VECTOUT?"); break; -- 2.7.4