[clang][AArch64] readd support for 'p' inline asm constraint

[nickdesaulniers]

Summary

Was accidentally removed by commit af64948e2a05 when it overrode
TargetInfo::convertConstraint.

Fixes: pr/45225

[nickdesaulniers]

clang/lib/Basic/Targets/AArch64.h

98

bah, need to return R for the previous case.

[sdesmalen]

LGTM!

clang/lib/Basic/Targets/AArch64.h

97

nit: does this need a default: break?

[nickdesaulniers]

• fix 'U' case

[nickdesaulniers]

@sdesmalen sorry, would you mind re-reviewing. I'm not comfortable landing with the previous version being reviewed and not the current one.

[nickdesaulniers]

clang/test/CodeGen/inline-asm-p-constraint.c

2

Does this need REQUIRES: aarch64-registered-target?

[echristo]

clang/test/CodeGen/inline-asm-p-constraint.c

2

It shouldn't unless it's calling into the backend somewhere.

[sdesmalen]

In D76297#1927053, @nickdesaulniers wrote:

@sdesmalen sorry, would you mind re-reviewing. I'm not comfortable landing with the previous version being reviewed and not the current one.

Sure, thanks for checking! LGTM!

clang/lib/Basic/Targets/AArch64.h

public:
   ArrayRef<TargetInfo::GCCRegAlias> getGCCRegAliases() const override;
 
   std::string convertConstraint(const char *&Constraint) const override {
     std::string R;
     switch (*Constraint) {
     case 'U': // Three-character constraint; add "@3" hint for later parsing.
       R = std::string("@3") + std::string(Constraint, 3);
       Constraint += 2;
       break;
-    default:
-      R = std::string(1, *Constraint);
-      break;
     }
-    return R;
+    return TargetInfo::convertConstraint(Constraint);
   }
 
   bool validateAsmConstraint(const char *&Name,
                              TargetInfo::ConstraintInfo &Info) const override;
   bool
   validateConstraintModifier(StringRef Constraint, char Modifier, unsigned Size,
                              std::string &SuggestedModifier) const override;
   const char *getClobbers() const override;

clang/test/CodeGen/inline-asm-p-constraint.c

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple aarch64-linux-gnu | FileCheck %s
+void foo(void* ptr) {
+  asm volatile("prfm pldl1keep, %a0\n" : : "p" (ptr));
+  // CHECK:     call void asm sideeffect "prfm pldl1keep, ${0:a}\0A", "r"(i8* %0)
+  // CHECK-NOT: call void asm sideeffect "prfm pldl1keep, ${0:a}\0A", "p"(i8* %0)
+}