[FrameLowering] Use MCRegister instead of Register in CalleeSavedInfo. NFC (llvm#128095)

Callee saved registers should always be phyiscal registers. They are
often passed directly to other functions that take MCRegister like
getMinimalPhysRegClass or TargetRegisterClass::contains.

Unfortunately, sometimes the MCRegister is compared to a Register which
gave an ambiguous comparison error when the MCRegister is on the LHS.
Adding a MCRegister==Register comparison operator created more ambiguous
comparison errors elsewhere. These cases were usually comparing against
a base or frame pointer register that is a physical register in a
Register. For those I added an explicit conversion of Register to
MCRegister to fix the error.

Author: topperc

clang/docs/ReleaseNotes.rst

@@ -147,6 +147,8 @@ Improvements to Clang's diagnostics
 - The ``-Wunsafe-buffer-usage`` warning has been updated to warn
   about unsafe libc function calls.  Those new warnings are emitted
   under the subgroup ``-Wunsafe-buffer-usage-in-libc-call``.
+- Diagnostics on chained comparisons (``a < b < c``) are now an error by default. This can be disabled with
+  ``-Wno-error=parentheses``.
 
 Improvements to Clang's time-trace
 ----------------------------------

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -7126,7 +7126,7 @@ def note_precedence_conditional_first : Note<
 
 def warn_consecutive_comparison : Warning<
   "comparisons like 'X<=Y<=Z' don't have their mathematical meaning">,
-  InGroup<Parentheses>;
+  InGroup<Parentheses>, DefaultError;
 
 def warn_enum_constant_in_bool_context : Warning<
   "converting the enum constant to a boolean">,

clang/test/Sema/bool-compare.c

@@ -85,7 +85,7 @@ void f(int x, int y, int z) {
   if ((a<y) != -1) {}// expected-warning {{comparison of constant -1 with boolean expression is always true}}
 
   if ((a<y) == z) {} // no warning
-  if (a>y<z)      {} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+  if (a>y<z)      {} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
   if ((a<y) > z)  {} // no warning
   if((a<y)>(z<y)) {} // no warning
   if((a<y)==(z<y)){} // no warning
@@ -145,7 +145,7 @@ void f(int x, int y, int z) {
   if (-1 !=(a<y)) {} // expected-warning {{comparison of constant -1 with boolean expression is always true}}
 
   if (z ==(a<y))  {}    // no warning
-  if (z<a>y)      {} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+  if (z<a>y)      {} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
   if (z > (a<y))  {}    // no warning
   if((z<y)>(a<y)) {}   // no warning
   if((z<y)==(a<y)){}  // no warning

clang/test/Sema/parentheses.cpp

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -Wparentheses -fsyntax-only -verify %s
-// RUN: %clang_cc1 -Wparentheses -fsyntax-only -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -Wno-error=parentheses -fsyntax-only -verify %s
+// RUN: %clang_cc1 -Wno-error=parentheses -fsyntax-only -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
 
 bool someConditionFunc();
 

clang/test/SemaCXX/bool-compare.cpp

@@ -98,7 +98,7 @@ void f(int x, int y, int z) {
   if ((a<y) != -1) {}// expected-warning {{comparison of constant -1 with expression of type 'bool' is always true}}
 
   if ((a<y) == z) {} // no warning
-  if (a>y<z)      {} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+  if (a>y<z)      {} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
   if ((a<y) > z)  {} // no warning
   if((a<y)>(z<y)) {} // no warning
   if((a<y)==(z<y)){} // no warning
@@ -159,7 +159,7 @@ void f(int x, int y, int z) {
   if (-1 !=(a<y)) {} // expected-warning {{comparison of constant -1 with expression of type 'bool' is always true}}
 
   if (z ==(a<y))  {} // no warning
-  if (z<a>y)      {} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+  if (z<a>y)      {} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
   if (z > (a<y))  {} // no warning
   if((z<y)>(a<y)) {} // no warning
   if((z<y)==(a<y)){} // no warning
@@ -186,8 +186,7 @@ template<typename T, typename U, typename V> struct X6 {
         return v; // expected-error{{cannot initialize return object of type}}
     }
     bool r;
-    // FIXME: We should warn here, DiagRuntimeBehavior does currently not detect this.
-    if(r<0){}
+    if(r<0){} // expected-warning {{result of comparison of constant 0 with expression of type 'bool' is always false}}
 
     if (T x = t) {
       t = x;

clang/test/SemaCXX/cxx2a-adl-only-template-id.cpp

@@ -27,7 +27,7 @@ int e = h<0>(q); // ok, found by unqualified lookup
 void fn() {
   f<0>(q);
   int f;
-  f<0>(q); // expected-error {{invalid operands to binary expression}} // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+  f<0>(q); // expected-error {{invalid operands to binary expression}} // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
 }
 
 void disambig() {

clang/test/SemaTemplate/typo-dependent-name.cpp

@@ -20,7 +20,7 @@ struct X : Base<T> {
   bool f(T other) {
     // A pair of comparisons; 'inner' is a dependent name so can't be assumed
     // to be a template.
-    return this->inner < other > ::z; // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+    return this->inner < other > ::z; // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
   }
 };
 

clang/test/SemaTemplate/typo-template-name.cpp

@@ -36,7 +36,7 @@ namespace InExpr {
 
     // These are valid expressions.
     foo<foo; // expected-warning {{self-comparison}}
-    foo<int()>(0); // expected-warning {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
+    foo<int()>(0); // expected-error {{comparisons like 'X<=Y<=Z' don't have their mathematical meaning}}
     foo<int(), true>(false);
     foo<Base{}.n;
   }

llvm/include/llvm/CodeGen/MachineFrameInfo.h

@@ -32,7 +32,7 @@ class AllocaInst;
 /// Callee saved reg can also be saved to a different register rather than
 /// on the stack by setting DstReg instead of FrameIdx.
 class CalleeSavedInfo {
-  Register Reg;
+  MCRegister Reg;
   union {
     int FrameIdx;
     unsigned DstReg;
@@ -58,7 +58,7 @@ class CalleeSavedInfo {
   explicit CalleeSavedInfo(unsigned R, int FI = 0) : Reg(R), FrameIdx(FI) {}
 
   // Accessors.
-  Register getReg()                        const { return Reg; }
+  MCRegister getReg()                      const { return Reg; }
   int getFrameIdx()                        const { return FrameIdx; }
   unsigned getDstReg()                     const { return DstReg; }
   void setFrameIdx(int FI) {

llvm/lib/CodeGen/LivePhysRegs.cpp

@@ -301,7 +301,7 @@ void llvm::recomputeLivenessFlags(MachineBasicBlock &MBB) {
       // the last instruction in the block.
       if (MI.isReturn() && MFI.isCalleeSavedInfoValid()) {
         for (const CalleeSavedInfo &Info : MFI.getCalleeSavedInfo()) {
-          if (Info.getReg() == Reg) {
+          if (Info.getReg() == Reg.asMCReg()) {
             IsNotLive = !Info.isRestored();
             break;
           }