[ARM, inline-asm] Fix ARMTargetLowering::getRegForInlineAsmConstraint to return

register class tGPRRegClass if the target is thumb1.

This commit fixes a crash that occurs during register allocation which was
triggered when a virtual register defined by an inline-asm instruction had to
be spilled.
 
rdar://problem/18740489

llvm-svn: 221178

llvm/lib/Target/ARM/ARMISelLowering.cpp

@@ -10557,6 +10557,8 @@ ARMTargetLowering::getRegForInlineAsmConstraint(const std::string &Constraint,
         return RCPair(0U, &ARM::hGPRRegClass);
       break;
     case 'r':
+      if (Subtarget->isThumb1Only())
+        return RCPair(0U, &ARM::tGPRRegClass);
       return RCPair(0U, &ARM::GPRRegClass);
     case 'w':
       if (VT == MVT::Other)

llvm/test/CodeGen/Thumb/inlineasm-thumb.ll

@@ -1,4 +1,4 @@
-; RUN: llc -mtriple=thumb-eabi %s -o - | FileCheck %s
+; RUN: llc -mtriple=thumb-eabi -no-integrated-as %s -o - | FileCheck %s
 
 define i32 @t1(i32 %x, i32 %y) nounwind {
 entry:
@@ -6,3 +6,14 @@ entry:
   %0 = tail call i32 asm "mov $0, $1", "=l,h"(i32 %y) nounwind
   ret i32 %0
 }
+
+; CHECK-LABEL: constraint_r:
+; CHECK: foo2 r{{[0-7]+}}, r{{[0-7]+}}
+
+define i32 @constraint_r() {
+entry:
+  %0 = tail call i32 asm sideeffect "movs $0, #1", "=r"()
+  tail call void asm sideeffect "foo1", "~{r0},~{r1},~{r2},~{r3},~{r4},~{r5},~{r6},~{r7}"()
+  %1 = tail call i32 asm sideeffect "foo2 $0, $1", "=r,r"(i32 %0)
+  ret i32 %1
+}