[x86][inline-asm]Extend support for memory reference expression

[coby]

Summary

Extend support for expressions which represent a variable access in ms-style inline-asm, to allow the incorporation of both registers and variables.
Currently, expression such as 'asm mov eax, [var + eax]' would have been reduced to the (equivalent of) 'asm mov eax, [var]'
This patch amends it
llvm counterpart: D35774

[coby]

superseded by D37412

lib/Sema/SemaStmtAsm.cpp

ExprResult Sema::LookupInlineAsmIdentifier(CXXScopeSpec &SS,
   // Otherwise, it needs to be a complete type.
   if (RequireCompleteExprType(Result.get(), diag::err_asm_incomplete_type)) {
     return ExprError();
   }
 
   fillInlineAsmTypeInfo(Context, T, Info);
 
   // We can work with the expression as long as it's not an r-value.
-  if (!Result.get()->isRValue())
+  if (!Result.get()->isRValue()) {
     Info.IsVarDecl = true;
+    Expr::EvalResult Eval;
+    if (Result.get()->EvaluateAsLValue(Eval, Context))
+      Info.IsGlobalLV = Eval.isGlobalLValue();
+  }
 
   return Result;
 }
 
 bool Sema::LookupInlineAsmField(StringRef Base, StringRef Member,
                                 unsigned &Offset, SourceLocation AsmLoc) {
   Offset = 0;
   SmallVector<StringRef, 2> Members;

test/CodeGen/ms-inline-asm-indirect-memory-ref.c

+// REQUIRES: x86-registered-target
+// RUN: %clang_cc1 %s -fasm-blocks -triple x86_64-unknown-linux-gnu -emit-llvm -o - | FileCheck %s
+
+int gVar;
+
+void t1() {
+  // CHECK: add eax, dword ptr gVar[eax]
+  __asm add eax, dword ptr gVar[eax]
+  // CHECK: add dword ptr gVar[eax], eax
+  __asm add dword ptr [eax+gVar], eax
+  // CHECK: add ebx, dword ptr gVar[ebx + $$270]
+  __asm add ebx, dword ptr gVar[271 - 82 + 81 + ebx]
+  // CHECK: add dword ptr gVar[ebx + $$828], ebx
+  __asm add dword ptr [ebx + gVar + 828], ebx
+  // CHECK: add ecx, dword ptr gVar[ecx + ecx * $$4 + $$4590]
+  __asm add ecx, dword ptr gVar[4590 + ecx + ecx*4]
+  // CHECK: add dword ptr gVar[ecx + ecx * $$8 + $$73], ecx
+  __asm add dword ptr [gVar + ecx + 45 + 23 - 53 + 60 - 2 + ecx*8], ecx
+  // CHECK: add gVar[ecx + ebx + $$7], eax
+  __asm add 1 + 1 + 2 + 3[gVar + ecx + ebx], eax
+}
+
+void t2() {
+  int lVar;
+  // CHECK: mov eax, dword ptr ${{[0-9]}}[eax]
+  __asm mov eax, dword ptr lVar[eax]
+  // CHECK: mov dword ptr ${{[0-9]}}[eax], eax
+  __asm mov dword ptr [eax+lVar], eax
+  // CHECK: mov ebx, dword ptr ${{[0-9]}}[ebx + $$270]
+  __asm mov ebx, dword ptr lVar[271 - 82 + 81 + ebx]
+  // CHECK: mov dword ptr ${{[0-9]}}[ebx + $$828], ebx
+  __asm mov dword ptr [ebx + lVar + 828], ebx
+  // CHECK: mov ${{[0-9]}}[ebx + $$47], eax
+  __asm mov 5 + 8 + 13 + 21[lVar + ebx], eax
+}
+

test/CodeGen/ms-inline-asm.c

 // CHECK: call void asm sideeffect inteldialect "mov eax, $$36$0", "*m,~{eax},~{dirflag},~{fpsr},~{flags}"([4 x i32]* %{{.*}})
   __asm { mov eax, 4*16+4[4 + arr + 4] }
 // CHECK: call void asm sideeffect inteldialect "mov eax, $$76$0", "*m,~{eax},~{dirflag},~{fpsr},~{flags}"([4 x i32]* %{{.*}})
   __asm { mov eax, 4*4[64 + arr + (2*32)] }
 // CHECK: call void asm sideeffect inteldialect "mov eax, $$144$0", "*m,~{eax},~{dirflag},~{fpsr},~{flags}"([4 x i32]* %{{.*}})
   __asm { mov eax, 4*(4-2)[64 + arr - 2*32] }
 // CHECK: call void asm sideeffect inteldialect "mov eax, $$8$0", "*m,~{eax},~{dirflag},~{fpsr},~{flags}"([4 x i32]* %{{.*}})
   __asm { mov eax, 32*(4-2)[arr - 2*32] }
-// CHECK: call void asm sideeffect inteldialect "mov eax, $$0$0", "*m,~{eax},~{dirflag},~{fpsr},~{flags}"([4 x i32]* %{{.*}})
+// CHECK: call void asm sideeffect inteldialect "mov eax, $0", "*m,~{eax},~{dirflag},~{fpsr},~{flags}"([4 x i32]* %{{.*}})
 }
 
 void cpuid() {
   __asm cpuid
 // CHECK-LABEL: define void @cpuid
 // CHECK: call void asm sideeffect inteldialect "cpuid", "~{eax},~{ebx},~{ecx},~{edx},~{dirflag},~{fpsr},~{flags}"()
 }
 

test/Sema/ms-inline-asm.c

 int t2(int *arr, int i) {
   __asm {
     mov eax, arr;
     mov eax, arr[0];
     mov eax, arr[1 + 2];
     mov eax, arr[1 + (2 * 5) - 3 + 1<<1];
   }
 
-  // expected-error@+1 {{cannot use base register with variable reference}}
-  __asm { mov eax, arr[ebp + 1 + (2 * 5) - 3 + 1<<1] }
-  // expected-error@+1 {{cannot use index register with variable reference}}
-  __asm { mov eax, arr[esi * 4] }
+  // expected-error@+1 {{Can't use a local variable with both base and index registers}}
+  __asm { mov eax, [i + eax + ebx] }
   // expected-error@+1 {{cannot use more than one symbol in memory operand}}
   __asm { mov eax, arr[i] }
   // expected-error@+1 {{cannot use more than one symbol in memory operand}}
   __asm { mov eax, global[i] }
 
   // FIXME: Why don't we diagnose this?
   // expected-Xerror@+1 {{cannot reference multiple local variables in assembly operand}}
   //__asm mov eax, [arr + i];