Emit a better error when running out of registers on inline asm.

The most likely case where this error happens is when the user specifies
too many register operands. Don't make it look like an internal LLVM bug
when we can see that the error is coming from an inline asm instruction.
For other instructions we keep the "ran out of registers" error.

llvm-svn: 192041

3 files changed, 7 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/RegAllocBase.cpp b/llvm/lib/CodeGen/RegAllocBase.cpp
index a912414ad2b..3ee58d45d72 100644
--- a/llvm/lib/CodeGen/RegAllocBase.cpp
+++ b/llvm/lib/CodeGen/RegAllocBase.cpp
@@ -106,7 +106,6 @@ void RegAllocBase::allocatePhysRegs() {
 
     if (AvailablePhysReg == ~0u) {
       // selectOrSplit failed to find a register!
-      const char *Msg = "ran out of registers during register allocation";
       // Probably caused by an inline asm.
       MachineInstr *MI;
       for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(VirtReg->reg);
@@ -114,9 +113,9 @@ void RegAllocBase::allocatePhysRegs() {
         if (MI->isInlineAsm())
           break;
       if (MI)
-        MI->emitError(Msg);
+        MI->emitError("inline assembly requires more registers than available");
       else
-        report_fatal_error(Msg);
+        report_fatal_error("ran out of registers during register allocation");
       // Keep going after reporting the error.
       VRM->assignVirt2Phys(VirtReg->reg,
                  RegClassInfo.getOrder(MRI->getRegClass(VirtReg->reg)).front());
diff --git a/llvm/lib/CodeGen/RegAllocFast.cpp b/llvm/lib/CodeGen/RegAllocFast.cpp
index 400025074ca..6c2e60b5c6e 100644
--- a/llvm/lib/CodeGen/RegAllocFast.cpp
+++ b/llvm/lib/CodeGen/RegAllocFast.cpp
@@ -569,7 +569,10 @@ RAFast::LiveRegMap::iterator RAFast::allocVirtReg(MachineInstr *MI,
   }
 
   // Nothing we can do. Report an error and keep going with a bad allocation.
-  MI->emitError("ran out of registers during register allocation");
+  if (MI->isInlineAsm())
+    MI->emitError("inline assembly requires more registers than available");
+  else
+    MI->emitError("ran out of registers during register allocation");
   definePhysReg(MI, *AO.begin(), regFree);
   return assignVirtToPhysReg(VirtReg, *AO.begin());
 }
diff --git a/llvm/test/CodeGen/X86/inline-asm-error.ll b/llvm/test/CodeGen/X86/inline-asm-error.ll
index 747a5891cf0..31fb190daf8 100644
--- a/llvm/test/CodeGen/X86/inline-asm-error.ll
+++ b/llvm/test/CodeGen/X86/inline-asm-error.ll
@@ -6,7 +6,7 @@
 ; RUN: FileCheck %s < %t3
 
 ; The register allocator must fail on this function.
-; CHECK: error: ran out of registers during register allocation
+; CHECK: error: inline assembly requires more registers than available
 
 define void @f(i32 %x0, i32 %x1, i32 %x2, i32 %x3, i32 %x4, i32 %x5, i32 %x6, i32 %x7, i32 %x8, i32 %x9) nounwind ssp {
 entry: