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Re: [i386, AVX-512F, pr58269] Partial fix for PR58269: properly initialize last EXT REX SSE register.


Hi Kirill,

Thanks for Ilya's input on the PR thread.

We've done some testing/checking across the Darwin versions last night and I've bootstrapped all langs including Ada, and tested the patch below (together with the fragment you posted earlier) on Darwin12.

>> On Fri, Sep 6, 2013 at 10:34 AM, Kirill Yukhin <kirill.yukhin@gmail.com> wrote:

>>> Here is a patch to fix pr58269.
>>> Actually this is not a full fix, but an obvious part.

Here's what I propose for the remainder of the fix (FAOD, I cannot approve the Darwin changes).

====

Darwin is supposed to follow the System V psABI for x86_64 and, AFAICT for Darwin9, 10, 11 and 12 it is complying for function calls involving xmm0-7 (additional float args are, indeed, placed on the stack).  Ergo, saving xmm8-15 in __builtin_apply_args() only consumes time and stack space - the content is not part of the call.

As a fall-back; if I've missed a subtlety and, for some reason, we need to adjust the xmm set saved for compatibility with an older (gcc-4.2 based) system compiler, then we can override SSE_REGPARM_MAX in i386/darwin*.h for the relevant system version.

Losing TARGET_MACHO conditional code is always nice :)

Mike: Actually, since this seems to have uncovered a pre-existing wrong code bug, perhaps (this part of the) fix should also be applied to open branches?

gcc:

	PR target/58269
	config/i386/i386.c (ix86_function_arg_regno_p): Make Darwin use the
	xmm register set described in the psABI.

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index a8d70bc..e68b3f9 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -5706,17 +5706,9 @@ ix86_function_arg_regno_p (int regno)
 		    && (regno < FIRST_SSE_REG + SSE_REGPARM_MAX)));
     }
 
-  if (TARGET_MACHO)
-    {
-      if (SSE_REGNO_P (regno) && TARGET_SSE)
-        return true;
-    }
-  else
-    {
-      if (TARGET_SSE && SSE_REGNO_P (regno)
-          && (regno < FIRST_SSE_REG + SSE_REGPARM_MAX))
-        return true;
-    }
+  if (TARGET_SSE && SSE_REGNO_P (regno)
+      && (regno < FIRST_SSE_REG + SSE_REGPARM_MAX))
+    return true;
 
   /* TODO: The function should depend on current function ABI but
      builtins.c would need updating then. Therefore we use the


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