[GrilledChips]

It's kind of funny. There are lots of architectures it killed (Alpha, PA-RISC, basically everything except SPARC because Sun was sceptical) but basically all of them have outlived it in the linux kernel.

It killed their manufacturing based on hype, where as they all established a firm install base before itanium ever got rolling, which has ensured they continue to be (halfheartedly) maintained.

[cbmuser]

Itanium was killed because unlike all the other architectures it puts a rather big burden on upstream developers due its complicated design (dual stack with growth into two directions, complicated compiler optimizations etc).

[usrusr]

I keep wondering if it perhaps simply appeared too early. These days it feels as if almost everything is either open source or runs in some form of JIT compile VM, or both. Back then it was a huge problem to require code to be compiled not just to the general architecture but to the specific model to be fast.

But today? Moving some of the adaptions from the hardware scheduler to process lifetime persistence (as in JIT VM) or even into the software distribution infrastructure could be delightfully transparent.

[vgatherps]

It would probably be even worse today. Dynamically discovering ILP “just works” even as memory gets slower and slower and slower. A CPU today can execute hundreds of instructions and many predicted branches ahead of a slow load. It would be impossible to statically schedule this (you don’t know what will/won’t be in cache), and difficult to try and hoist all loads 100 instructions in advance especially when you take branching behavior into account.

GPUs have taken over much of the niche where these processors excel, number crunching where you have entirely pre-determined memory / compute access patterns.

[anarazel]

For GPUs it only really works because the code is translated to the relevant instruction steam close to the time of executing, where you can afford to optimize in a highly uarch specific way. Whereas VLIW at the time of itanium never was in that position... It just doesn't compute for me how Intel thought this was a good plan. It's not like they didn't know that existing compiled binaries are going to continue being used on newer uarchs

[p_l]

The critical part was less VLIW, and more EPIC - the Explicit Parallel part. There were previous VLIW arches that didn't have issues with compilers, one of them afaik even formed backbone of many advanced optimizing compilers in 1990s because the vendor licensed the compiler tech to others.