PowerPC: Add SPE floating point min/max instructions (efsmax, efsmin)

[daskey]

#6863 (partial)

Adds support for SPE floating-point min/max instructions (from e200z759CRM):

• efsmax: Floating-Point Single-Precision Maximum
• efsmin: Floating-Point Single-Precision Minimum

Example:

Assembly:
efsmin r5,r3,r4 # r5 = min(r3, r4)
efsmax r5,r3,r4 # r5 = max(r3, r4)

Decompiles to:
// efsmin
result = fA;
if (fB < fA) {
result = fB;
}

// efsmax
result = fA;
if (fA < fB) {
result = fB;
}

[Copilot]

Pull request overview

This PR adds support for two SPE (Signal Processing Engine) floating-point instructions for PowerPC processors: efsmax (floating-point maximum) and efsmin (floating-point minimum). These instructions operate on single-precision floating-point values stored in the lower 32-bit word of 64-bit registers.

Key Changes:

• Implementation of efsmax instruction (opcode 0x2B0) that selects the maximum of two single-precision floats
• Implementation of efsmin instruction (opcode 0x2B1) that selects the minimum of two single-precision floats

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[GhidorahRex]

We try to avoid using unnecessary gotos for these kind of operations. The slightly more preferred way to do it is to have a conditional assignment:

   local cond:1 = A:4 f>= B:4;
   result = (zext(cond) * A:4) + (zext(!cond) * B:4);

Although I don't have a binary to test and demonstrate this on.

EDIT: Also as good practice, we should avoid doing multiple reads of the input registers as well, so here's what it might look like with that change too:

:efsmax D,A,B is OP=4 & D & A & B & XOP_0_10=0x2B0
{
   local inA:4 = A:4;
   local inB:4 = B:4;
   local cond:1 = inA f>= inB;
   local result:4 = (zext(cond) * inA) + (zext(!cond) * inB);
   # assign to lower word of D
   D = ( D & 0xFFFFFFFF00000000 ) | zext( result );
   setFPRF( result );
   setSummaryFPSCR();
}

[GhidorahRex]

Similarly here

   local cond:1 = A:4 f<= B:4;
   result = (zext(cond) * A:4) + (zext(!cond) * B:4);

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

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