Merging r340666:

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r340666 | hans | 2018-08-25 00:46:33 +0200 (Sat, 25 Aug 2018) | 21 lines

Revert r323281 "Adjust MaxAtomicInlineWidth for i386/i486 targets."

As reported on http://lists.llvm.org/pipermail/cfe-dev/2018-August/058760.html,
this broke i386-freebsd11 due to its lack of atomic 64 bit primitives.

While that's not really this commit's fault, let's revert back to the old
behaviour until this can be fixed. This means generating cmpxchg8b etc for i386
and i486 which don't technically support those, but that's been the behaviour
for a long time, so a little longer probably doesn't hurt that much.

> Adjust MaxAtomicInlineWidth for i386/i486 targets.
>
> This is to fix the bug reported in https://bugs.llvm.org/show_bug.cgi?id=34347#c6.
> Currently, all  MaxAtomicInlineWidth of x86-32 targets are set to 64. However,
> i386 doesn't support any cmpxchg related instructions. i486 only supports cmpxchg.
> So in this patch MaxAtomicInlineWidth is reset as follows:
> For i386, the MaxAtomicInlineWidth should be 0 because no cmpxchg is supported.
> For i486, the MaxAtomicInlineWidth should be 32 because it supports cmpxchg.
> For others 32 bits x86 cpu, the MaxAtomicInlineWidth should be 64 because of cmpxchg8b.
>
> Differential Revision: https://reviews.llvm.org/D42154
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git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_70@340667 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Basic/Targets/X86.h b/lib/Basic/Targets/X86.h
index 019bc8d51a634cab6c45440bc476626ebddca98e..1d23b0ef693336958c04df00208528a459ef1d97 100644 (file)
--- a/lib/Basic/Targets/X86.h
+++ b/lib/Basic/Targets/X86.h
@@ -350,11 +350,9 @@ public:
          (1 << TargetInfo::LongDouble));
 
     // x86-32 has atomics up to 8 bytes
-    CPUKind Kind = getCPUKind(Opts.CPU);
-    if (Kind >= CK_i586 || Kind == CK_Generic)
-      MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64;
-    else if (Kind >= CK_i486)
-      MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 32;
+    // FIXME: Check that we actually have cmpxchg8b before setting
+    // MaxAtomicInlineWidth. (cmpxchg8b is an i586 instruction.)
+    MaxAtomicPromoteWidth = MaxAtomicInlineWidth = 64;
   }
 
   BuiltinVaListKind getBuiltinVaListKind() const override {

diff --git a/test/CodeGenCXX/atomic-inline.cpp b/test/CodeGenCXX/atomic-inline.cpp
index 327f85d5667fdf7bf3e3b92cfa775a5058909d65..fe727589d2e275409d967c587989deed4f994010 100644 (file)
--- a/test/CodeGenCXX/atomic-inline.cpp
+++ b/test/CodeGenCXX/atomic-inline.cpp
@@ -1,52 +1,6 @@
 // RUN: %clang_cc1 %s -std=c++11 -emit-llvm -o - -triple=x86_64-linux-gnu | FileCheck %s
 // RUN: %clang_cc1 %s -std=c++11 -emit-llvm -o - -triple=x86_64-linux-gnu -target-cpu core2 | FileCheck %s --check-prefix=CORE2
-// RUN: %clang_cc1 %s -std=c++11 -emit-llvm -o - -triple=i386-linux-gnu -target-cpu i386 | FileCheck %s --check-prefix=I386
-// RUN: %clang_cc1 %s -std=c++11 -emit-llvm -o - -triple=i386-linux-gnu -target-cpu i486 | FileCheck %s --check-prefix=I486
-// Check the atomic code generation for cpu targets w/wo cx, cx8 and cx16 support.
-
-struct alignas(4) AM4 {
-  short f1, f2;
-};
-AM4 m4;
-AM4 load4() {
-  AM4 am;
-  // CHECK-LABEL: @_Z5load4v
-  // CHECK: load atomic i32, {{.*}} monotonic
-  // CORE2-LABEL: @_Z5load4v
-  // CORE2: load atomic i32, {{.*}} monotonic
-  // I386-LABEL: @_Z5load4v
-  // I386: call i32 @__atomic_load_4
-  // I486-LABEL: @_Z5load4v
-  // I486: load atomic i32, {{.*}} monotonic
-  __atomic_load(&m4, &am, 0);
-  return am;
-}
-
-AM4 s4;
-void store4() {
-  // CHECK-LABEL: @_Z6store4v
-  // CHECK: store atomic i32 {{.*}} monotonic
-  // CORE2-LABEL: @_Z6store4v
-  // CORE2: store atomic i32 {{.*}} monotonic
-  // I386-LABEL: @_Z6store4v
-  // I386: call void @__atomic_store_4
-  // I486-LABEL: @_Z6store4v
-  // I486: store atomic i32 {{.*}} monotonic
-  __atomic_store(&m4, &s4, 0);
-}
-
-bool cmpxchg4() {
-  AM4 am;
-  // CHECK-LABEL: @_Z8cmpxchg4v
-  // CHECK: cmpxchg i32* {{.*}} monotonic
-  // CORE2-LABEL: @_Z8cmpxchg4v
-  // CORE2: cmpxchg i32* {{.*}} monotonic
-  // I386-LABEL: @_Z8cmpxchg4v
-  // I386: call zeroext i1 @__atomic_compare_exchange_4
-  // I486-LABEL: @_Z8cmpxchg4v
-  // I486: cmpxchg i32* {{.*}} monotonic
-  return __atomic_compare_exchange(&m4, &s4, &am, 0, 0, 0);
-}
+// Check the atomic code generation for cpu targets w/wo cx16 support.
 
 struct alignas(8) AM8 {
   int f1, f2;
@@ -58,10 +12,6 @@ AM8 load8() {
   // CHECK: load atomic i64, {{.*}} monotonic
   // CORE2-LABEL: @_Z5load8v
   // CORE2: load atomic i64, {{.*}} monotonic
-  // I386-LABEL: @_Z5load8v
-  // I386: call i64 @__atomic_load_8
-  // I486-LABEL: @_Z5load8v
-  // I486: call i64 @__atomic_load_8
   __atomic_load(&m8, &am, 0);
   return am;
 }
@@ -72,10 +22,6 @@ void store8() {
   // CHECK: store atomic i64 {{.*}} monotonic
   // CORE2-LABEL: @_Z6store8v
   // CORE2: store atomic i64 {{.*}} monotonic
-  // I386-LABEL: @_Z6store8v
-  // I386: call void @__atomic_store_8
-  // I486-LABEL: @_Z6store8v
-  // I486: call void @__atomic_store_8
   __atomic_store(&m8, &s8, 0);
 }
 
@@ -85,10 +31,6 @@ bool cmpxchg8() {
   // CHECK: cmpxchg i64* {{.*}} monotonic
   // CORE2-LABEL: @_Z8cmpxchg8v
   // CORE2: cmpxchg i64* {{.*}} monotonic
-  // I386-LABEL: @_Z8cmpxchg8v
-  // I386: call zeroext i1 @__atomic_compare_exchange_8
-  // I486-LABEL: @_Z8cmpxchg8v
-  // I486: call zeroext i1 @__atomic_compare_exchange_8
   return __atomic_compare_exchange(&m8, &s8, &am, 0, 0, 0);
 }
 
@@ -124,3 +66,4 @@ bool cmpxchg16() {
   // CORE2: cmpxchg i128* {{.*}} monotonic
   return __atomic_compare_exchange(&m16, &s16, &am, 0, 0, 0);
 }
+