This change is mainly to benefit 32-bit systems where SSE support can't be assumed by default, but with the i965 driver, more often than not it can be assumed an Intel Core 2 processor or newer is in use. (The older Intel processors are generally using the i915 driver.) By setting the -march=core2 flag, for i386 builds SSE would now be used for floating-point math and cmov instructions, plus other performance optimizations.
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This patch was ultimately rejected since it turns out there's still some old Pentium 4s that could be found in an i965 driver configuration where things might break.
[...]
This patch was ultimately rejected since it turns out there's still some old Pentium 4s that could be found in an i965 driver configuration where things might break.
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