Larry, you can correct me here, but it was when Sun finally wrote their own - learning from DEC [and Masscomp] that the real Bill Wulf' Green book style optimizer with its C compiler generated better code than the PCC ones. Unfortunately, Sun's marketing (also ex-DEC) decided it could be a revenue source. Unlike Masscomp, where we said to our ex-DEC marketing types— "Charge for the Fortran if you want to, but C is part of the system."
IIRC: Sun continued to bundled a simple C compiler so you build the kernel, but it was trying to make $s on the compiler suite.
SW economics can be difficult. Application firms like CAD or tools firms, of course, make all their money on their SW. But systems companies make their money on the HW and need the compilers to generate the applications to build the ecosystem to sell the HW. Funny thing, I have always said huge reason BLISS lost was that DEC charged for $5000 per CPU for it on TOPS or VMS, while C was free with UNIX - even though the difference is the resulting code was remarkable. So many people stayed away because they did not want to spend the extra $s.