For 64-bit the rest of the general regs are ok for the q constraint. …

…Make

sure we can emit both the high and low versions of those registers.

Fixes rdar://10392864

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145579 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86RegisterInfo.cpp

@@ -665,7 +665,7 @@ unsigned getX86SubSuperRegister(unsigned Reg, EVT VT, bool High) {
   case MVT::i8:
     if (High) {
       switch (Reg) {
-      default: return 0;
+      default: return getX86SubSuperRegister(Reg, MVT::i64, High);
       case X86::AH: case X86::AL: case X86::AX: case X86::EAX: case X86::RAX:
         return X86::AH;
       case X86::DH: case X86::DL: case X86::DX: case X86::EDX: case X86::RDX:
@@ -785,6 +785,22 @@ unsigned getX86SubSuperRegister(unsigned Reg, EVT VT, bool High) {
       return X86::R15D;
     }
   case MVT::i64:
+    // For 64-bit mode if we've requested a "high" register and the
+    // Q or r constraints we want one of these high registers or
+    // just the register name otherwise.
+    if (High) {
+      switch (Reg) {
+      case X86::SIL: case X86::SI: case X86::ESI: case X86::RSI:
+        return X86::SI;
+      case X86::DIL: case X86::DI: case X86::EDI: case X86::RDI:
+        return X86::DI;
+      case X86::BPL: case X86::BP: case X86::EBP: case X86::RBP:
+        return X86::BP;
+      case X86::SPL: case X86::SP: case X86::ESP: case X86::RSP:
+        return X86::SP;
+      // Fallthrough.
+      }
+    }
     switch (Reg) {
     default: return Reg;
     case X86::AH: case X86::AL: case X86::AX: case X86::EAX: case X86::RAX:

test/CodeGen/X86/inline-asm-q-regs.ll

@@ -20,3 +20,10 @@ define void @test3(double %tmp) nounwind {
   call void asm sideeffect "$0", "q"(double %tmp) nounwind
   ret void
 }
+
+; rdar://10392864
+define void @test4(i8 signext %val, i8 signext %a, i8 signext %b, i8 signext %c, i8 signext %d) nounwind {
+entry:
+  %0 = tail call { i8, i8, i8, i8, i8 } asm "foo $1, $2, $3, $4, $1\0Axchgb ${0:b}, ${0:h}", "=q,={ax},={bx},={cx},={dx},0,1,2,3,4,~{dirflag},~{fpsr},~{flags}"(i8 %val, i8 %a, i8 %b, i8 %c, i8 %d) nounwind
+  ret void
+}