[llvm] AMDGPU/GlobalISel: Disable LCSSA pass (PR #124297)

[Matt Arsenault via llvm-commits]

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@@ -1366,7 +1366,8 @@ bool GCNPassConfig::addPreISel() {
   // control flow modifications.
   addPass(createAMDGPURewriteUndefForPHILegacyPass());
 
-  addPass(createLCSSAPass());
+  if (!getCGPassBuilderOption().EnableGlobalISelOption)
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arsenm wrote:

You can't just disable a pass for only globalisel. This will break the dag if there is a fallback 

https://github.com/llvm/llvm-project/pull/124297