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Re: [PATCH 21/27] arcv3: TCG instruction generator changes


From: Richard Henderson
Subject: Re: [PATCH 21/27] arcv3: TCG instruction generator changes
Date: Wed, 7 Apr 2021 16:43:56 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1

On 4/5/21 7:31 AM, cupertinomiranda@gmail.com wrote:
+        if(ctx->insn.limm & 0x80000000)
+          ctx->insn.limm += 0xffffffff00000000;

(1) bad braces, but
(2) use an unconditional cast to int32_t.

Qemu forces the compiler to use standard 2's compliment arithmetic. We don't have to go out of our way to work around the ISO-C lunacy of "undefined values" that for no good reason still allows sign-magnitude and 1's compliment arithmetic.

+    if (ctx->insn.cc) {
+        TCGv cc = tcg_temp_local_new();
+        arc_gen_verifyCCFlag(ctx, cc);
+        tcg_gen_brcondi_tl(TCG_COND_NE, cc, 1, done);
+        tcg_temp_free(cc);
+    }
+

Lots of non-uses of gen_cc_prologue/epilogue.


r~



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