[PATCH] D77542: [PowerPC] Treat 'Z' inline asm constraint as a true memory constraint

[Nemanja Ivanovic via Phabricator via cfe-commits]

nemanjai created this revision.
nemanjai added reviewers: hfinkel, PowerPC.
Herald added subscribers: cfe-commits, shchenz, kbarton.
Herald added a project: clang.

We currently emit incorrect codegen for this constraint because we set it as a constraint that allows registers. This will cause the value to be copied to the stack and that address to be passed as the address. This is not what we want.

Fixes: https://bugs.llvm.org/show_bug.cgi?id=42762


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D77542

Files:
  clang/lib/Basic/Targets/PPC.h
  clang/test/CodeGen/ppc64-inline-asm.c


Index: clang/test/CodeGen/ppc64-inline-asm.c
===================================================================
--- clang/test/CodeGen/ppc64-inline-asm.c
+++ clang/test/CodeGen/ppc64-inline-asm.c
@@ -37,3 +37,16 @@
 // CHECK-LABEL: double @test_fmax(double %x, double %y)
 // CHECK: call double asm "xsmaxdp ${0:x}, ${1:x}, ${2:x}", "=^ws,^ws,^ws"(double %x, double %y)
 }
+
+void testZ(void *addr) {
+  asm volatile ("dcbz %y0\n" :: "Z"(*(unsigned char *)addr) : "memory");
+// CHECK-LABEL: void @testZ(i8* %addr)
+// CHECK: call void asm sideeffect "dcbz ${0:y}\0A", "*Z,~{memory}"(i8* %addr)
+}
+
+void testZwOff(void *addr, long long off) {
+  asm volatile ("dcbz %y0\n" :: "Z"(*(unsigned char *)(addr + off)) : "memory");
+// CHECK-LABEL: void @testZwOff(i8* %addr, i64 %off)
+// CHEC: %[[VAL:[^ ]+]] = getelementptr i8, i8* %addr, i64 %off
+// CHEC: call void asm sideeffect "dcbz ${0:y}\0A", "*Z,~{memory}"(i8* %[[VAL]])
+}
Index: clang/lib/Basic/Targets/PPC.h
===================================================================
--- clang/lib/Basic/Targets/PPC.h
+++ clang/lib/Basic/Targets/PPC.h
@@ -276,11 +276,12 @@
       break;
     case 'Q': // Memory operand that is an offset from a register (it is
               // usually better to use `m' or `es' in asm statements)
+      Info.setAllowsRegister();
+      LLVM_FALLTHROUGH;
     case 'Z': // Memory operand that is an indexed or indirect from a
               // register (it is usually better to use `m' or `es' in
               // asm statements)
       Info.setAllowsMemory();
-      Info.setAllowsRegister();
       break;
     case 'R': // AIX TOC entry
     case 'a': // Address operand that is an indexed or indirect from a


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