So I feel like I need to write a blog post about this, but succinctly I think there's a good argument to be made that the issue wasn't the compiler despite popular wisdom. I don't even think it was the nature of unpredictable memory access times either as the itanium has a ton of special architectural hardware to handle unpredictable memory accesses (a lot of which are essentially some of the primitives that an OoO core uses for internal bookkeeping, just exposed architecturally).
I just think the arch has a similarity to archs like cell where it was planned for a world without the end of dennard scaling and just stopped making sense when we weren't targeting scaling to 10Ghz consumer CPUs and beyond.
The relatively fixed clock period that makes sense post ~2006 also means that the CPU architecture of that made the most sense ~2006 (Tomasulo OoO cores) continues to make sense, with most of the process gains going to just making bigger, wider cores.
I just think the arch has a similarity to archs like cell where it was planned for a world without the end of dennard scaling and just stopped making sense when we weren't targeting scaling to 10Ghz consumer CPUs and beyond.
The relatively fixed clock period that makes sense post ~2006 also means that the CPU architecture of that made the most sense ~2006 (Tomasulo OoO cores) continues to make sense, with most of the process gains going to just making bigger, wider cores.