Uh ... working around this in each and every piece of software sounds like a non-starter? Intel should be on the hook to fix this.

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Polizeiposaune 6 hours ago | parent [-]

Use of the "h" register slices (bits 8..15) by compilers is thankfully pretty rare -- otherwise this would have been noticed much sooner!

Agner Fog's optimization guide says "Any use of the high 8-bit registers AH, BH, CH, DH should be avoided because it can cause false dependences and less efficient code."

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userbinator 6 hours ago | parent [-]

Use of the "h" register slices (bits 8..15) by compilers is thankfully pretty rare

That's unfortunate, because it's precisely why things like this will keep happening.

Agner Fog's optimization guide says "Any use of the high 8-bit registers AH, BH, CH, DH should be avoided because it can cause false dependences and less efficient code."

The sad vicious cycle of compilers not exercising the hardware, and then the hardware designers not paying attention. Using the high 8-bit registers and "implicitly merging" them is one of the ways to reduce the number of instructions and thus improve size optimisation.

	▲	fuhsnn 2 hours ago \| parent [-]
		> The sad vicious cycle of compilers not exercising the hardware There could theoretically be instruction selection passes that are biased toward rare instructions, specialized for fuzzing hardware, I'm surprised Intel doesn't already do that.