[llvm] [X86][GlobalISel] Enable G_BUILD_VECTOR and G_CONSTANT_POOL (PR #92844)

[Matt Arsenault via llvm-commits]

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@@ -505,6 +505,9 @@ bool X86PassConfig::addRegBankSelect() {
 
 bool X86PassConfig::addGlobalInstructionSelect() {
   addPass(new InstructionSelect(getOptLevel()));
+  // Add GlobalBaseReg in case there is no SelectionDAG passes afterwards
+  if (isGlobalISelAbortEnabled())
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arsenm wrote:

I read this backwards, but I guess this is just mirroring how the fallback pipeline is added. It might make sense to have a separate post-isel insert point 

https://github.com/llvm/llvm-project/pull/92844