[mips] Support 16-bit offsets for 'm' inline assembly memory constraint.

[vkalintiris]

LGTM.

lib/Target/Mips/MipsSEISelDAGToDAG.cpp

SelectInlineAsmMemoryOperand(const SDValue &Op, unsigned ConstraintID,
                              std::vector<SDValue> &OutOps) {
   SDValue Base, Offset;
 
   switch(ConstraintID) {
   default:
     llvm_unreachable("Unexpected asm memory constraint");
   // All memory constraints can at least accept raw pointers.
   case InlineAsm::Constraint_i:
-  case InlineAsm::Constraint_m:
   case InlineAsm::Constraint_R:
     OutOps.push_back(Op);
     OutOps.push_back(CurDAG->getTargetConstant(0, MVT::i32));
     return false;
+  case InlineAsm::Constraint_m:
+    if (selectAddrRegImm16(Op, Base, Offset)) {
+      OutOps.push_back(Base);
+      OutOps.push_back(Offset);
+      return false;
+    }
+    OutOps.push_back(Op);
+    OutOps.push_back(CurDAG->getTargetConstant(0, MVT::i32));
+    return false;
   case InlineAsm::Constraint_ZC:
     // ZC matches whatever the pref, ll, and sc instructions can handle for the
     // given subtarget.
     if (Subtarget->inMicroMipsMode()) {
       // On microMIPS, they can handle 12-bit offsets.
       if (selectAddrRegImm12(Op, Base, Offset)) {
         OutOps.push_back(Base);
         OutOps.push_back(Offset);

test/CodeGen/Mips/inlineasm_constraint_m.ll

+; RUN: llc -march=mipsel < %s | FileCheck %s
+
+@data = global [8193 x i32] zeroinitializer
+
+define void @m(i32 *%p) nounwind {
+entry:
+  ; CHECK-LABEL: m:
+
+  call void asm sideeffect "lw $$1, $0", "*m,~{$1}"(i32* getelementptr inbounds ([8193 x i32], [8193 x i32]* @data, i32 0, i32 0))
+
+  ; CHECK: lw $[[BASEPTR:[0-9]+]], %got(data)(
+  ; CHECK: #APP
+  ; CHECK: lw $1, 0($[[BASEPTR]])
+  ; CHECK: #NO_APP
+
+  ret void
+}
+
+define void @m_offset_4(i32 *%p) nounwind {
+entry:
+  ; CHECK-LABEL: m_offset_4:
+
+  call void asm sideeffect "lw $$1, $0", "*m,~{$1}"(i32* getelementptr inbounds ([8193 x i32], [8193 x i32]* @data, i32 0, i32 1))
+
+  ; CHECK: lw $[[BASEPTR:[0-9]+]], %got(data)(
+  ; CHECK: #APP
+  ; CHECK: lw $1, 4($[[BASEPTR]])
+  ; CHECK: #NO_APP
+
+  ret void
+}
+
+define void @m_offset_32764(i32 *%p) nounwind {
+entry:
+  ; CHECK-LABEL: m_offset_32764:
+
+  call void asm sideeffect "lw $$1, $0", "*m,~{$1}"(i32* getelementptr inbounds ([8193 x i32], [8193 x i32]* @data, i32 0, i32 8191))
+
+  ; CHECK-DAG: lw $[[BASEPTR:[0-9]+]], %got(data)(
+  ; CHECK: #APP
+  ; CHECK: lw $1, 32764($[[BASEPTR]])
+  ; CHECK: #NO_APP
+
+  ret void
+}
+
+define void @m_offset_32768(i32 *%p) nounwind {
+entry:
+  ; CHECK-LABEL: m_offset_32768:
+
+  call void asm sideeffect "lw $$1, $0", "*m,~{$1}"(i32* getelementptr inbounds ([8193 x i32], [8193 x i32]* @data, i32 0, i32 8192))
+
+  ; CHECK-DAG: lw $[[BASEPTR:[0-9]+]], %got(data)(
+  ; CHECK-DAG: ori $[[T0:[0-9]+]], $zero, 32768
+  ; CHECK: addu $[[BASEPTR2:[0-9]+]], $[[BASEPTR]], $[[T0]]
+  ; CHECK: #APP
+  ; CHECK: lw $1, 0($[[BASEPTR2]])
+  ; CHECK: #NO_APP
+
+  ret void
+}

test/CodeGen/Mips/inlineasmmemop.ll

 ; RUN: llc -march=mipsel < %s | FileCheck %s
 
 ; Simple memory
 @g1 = external global i32
 
 define i32 @f1(i32 %x) nounwind {
 entry:
 ; CHECK-LABEL: f1:
-; CHECK: addiu $[[T0:[0-9]+]], $sp
 ; CHECK: #APP
-; CHECK: sw $4, 0($[[T0]])
+; CHECK: sw $4, [[OFFSET:[0-9]+]]($sp)
 ; CHECK: #NO_APP
+; CHECK: lw  $[[T1:[0-9]+]], %got(g1)
 ; CHECK: #APP
-; CHECK: lw $[[T3:[0-9]+]], 0($[[T0]])
+; CHECK: lw $[[T3:[0-9]+]], [[OFFSET]]($sp)
 ; CHECK: #NO_APP
-; CHECK: lw  $[[T1:[0-9]+]], %got(g1)
 ; CHECK: sw  $[[T3]], 0($[[T1]])
 
   %l1 = alloca i32, align 4
   call void asm "sw $1, $0", "=*m,r"(i32* %l1, i32 %x) nounwind
   %0 = call i32 asm "lw $0, $1", "=r,*m"(i32* %l1) nounwind
   store i32 %0, i32* @g1, align 4
   ret i32 %0
 }
 
 ; CHECK-LABEL: main:
 ; "D": Second word of a double word. This works for any memory element
 ; double or single.
 ; CHECK: #APP
-; CHECK: lw ${{[0-9]+}},4(${{[0-9]+}});
+; CHECK: lw ${{[0-9]+}}, 16(${{[0-9]+}});
 ; CHECK: #NO_APP
 
 ; No "D": First word of a double word. This works for any memory element
 ; double or single.
 ; CHECK: #APP
-; CHECK: lw ${{[0-9]+}},0(${{[0-9]+}});
+; CHECK: lw ${{[0-9]+}}, 12(${{[0-9]+}});
 ; CHECK: #NO_APP
 
 @b = common global [20 x i32] zeroinitializer, align 4
 
 define void @main() {
 entry:
 ; Second word:
-  tail call void asm sideeffect "    lw    $0,${1:D};", "r,*m,~{$11}"(i32 undef, i32* getelementptr inbounds ([20 x i32], [20 x i32]* @b, i32 0, i32 3))
+  tail call void asm sideeffect "    lw    $0, ${1:D};", "r,*m,~{$11}"(i32 undef, i32* getelementptr inbounds ([20 x i32], [20 x i32]* @b, i32 0, i32 3))
 ; First word. Notice, no 'D':
-  tail call void asm sideeffect "    lw    $0,${1};", "r,*m,~{$11}"(i32 undef, i32* getelementptr inbounds ([20 x i32], [20 x i32]* @b, i32 0, i32 3))
+  tail call void asm sideeffect "    lw    $0, ${1};", "r,*m,~{$11}"(i32 undef, i32* getelementptr inbounds ([20 x i32], [20 x i32]* @b, i32 0, i32 3))
   ret void
 }