[llvm] [GlobalISel] Diagnose inline assembly constraint lowering errors (PR #135782)

[Matt Arsenault via llvm-commits]

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@@ -344,9 +355,8 @@ bool InlineAsmLowering::lowerInlineAsm(
 
         // Find a register that we can use.
         if (OpInfo.Regs.empty()) {
-          LLVM_DEBUG(dbgs()
-                     << "Couldn't allocate output register for constraint\n");
-          return false;
+          return reportInlineAsmConstraintError(
+              Call, OpInfo, "couldn't allocate output register for constraint");
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arsenm wrote:

although should just fix this now, it's upgrading it to a user facing string 

https://github.com/llvm/llvm-project/pull/135782