[clang] aede24e - [PowerPC] Treat 'Z' inline asm constraint as a true memory constraint

[Nemanja Ivanovic via cfe-commits]

Author: Nemanja Ivanovic
Date: 2020-05-22T07:59:21-05:00
New Revision: aede24ecaa08db806fb173faf2de9cff95df8cee

URL: https://github.com/llvm/llvm-project/commit/aede24ecaa08db806fb173faf2de9cff95df8cee
DIFF: https://github.com/llvm/llvm-project/commit/aede24ecaa08db806fb173faf2de9cff95df8cee.diff

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

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

Differential revision: https://reviews.llvm.org/D77542

Added: 
    

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

Removed: 
    


################################################################################
diff  --git a/clang/lib/Basic/Targets/PPC.h b/clang/lib/Basic/Targets/PPC.h
index 6261a49c4fde..7c19a96a99c7 100644
--- a/clang/lib/Basic/Targets/PPC.h
+++ b/clang/lib/Basic/Targets/PPC.h
@@ -276,11 +276,12 @@ class LLVM_LIBRARY_VISIBILITY PPCTargetInfo : public TargetInfo {
       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

diff  --git a/clang/test/CodeGen/ppc64-inline-asm.c b/clang/test/CodeGen/ppc64-inline-asm.c
index 3e958c328f92..0b32d0bf4820 100644
--- a/clang/test/CodeGen/ppc64-inline-asm.c
+++ b/clang/test/CodeGen/ppc64-inline-asm.c
@@ -37,3 +37,16 @@ double test_fmax(double x, double y) {
 // 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)
+// CHECK: %[[VAL:[^ ]+]] = getelementptr i8, i8* %addr, i64 %off
+// CHECK: call void asm sideeffect "dcbz ${0:y}\0A", "*Z,~{memory}"(i8* %[[VAL]])
+}