[PPC64] Add support for the ICBT instruction on POWER8.

Patch by Kit Barton.

Support for the ICBT instruction is currently present, but limited to
embedded processors. This change adds a new FeatureICBT that can be used
to identify whether the ICBT instruction is available on a specific processor.

Two new tests are added:
 * Positive test to ensure the icbt instruction is present when using
-mcpu=pwr8
 * Negative test to ensure the icbt instruction is not generated when
using -mcpu=pwr7

Both test cases use the Prefetch opcode in LLVM. They are based on the
ppc64-prefetch.ll test case.

llvm-svn: 226033

2 files changed, 35 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/PowerPC/ppc64-icbt-pwr7.ll b/llvm/test/CodeGen/PowerPC/ppc64-icbt-pwr7.ll
new file mode 100644
index 00000000000..e8617ccfc8a
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/ppc64-icbt-pwr7.ll
@@ -0,0 +1,19 @@
+; Test the ICBT instruction is not emitted on POWER7
+; Based on the ppc64-prefetch.ll test
+; RUN: not llc -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr7 < %s 2>&1 | FileCheck %s
+ 
+declare void @llvm.prefetch(i8*, i32, i32, i32)
+
+define void @test(i8* %a, ...) nounwind {
+entry:
+  call void @llvm.prefetch(i8* %a, i32 0, i32 3, i32 0)
+  ret void
+
+; FIXME: Crashing is not really the correct behavior here, we really should just emit nothing
+; CHECK: Cannot select: 0x{{[0-9,a-f]+}}: ch = Prefetch 
+; CHECK: 0x{{[0-9,a-f]+}}: i32 = Constant<0> 
+; CHECK-NEXT: 0x{{[0-9,a-f]+}}: i32 = Constant<3>
+; CHECK-NEXT: 0x{{[0-9,a-f]+}}: i32 = Constant<0>
+
+}
+
diff --git a/llvm/test/CodeGen/PowerPC/ppc64-icbt-pwr8.ll b/llvm/test/CodeGen/PowerPC/ppc64-icbt-pwr8.ll
new file mode 100644
index 00000000000..a0f084a6bf9
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/ppc64-icbt-pwr8.ll
@@ -0,0 +1,16 @@
+; Test the ICBT instruction on POWER8
+; Copied from the ppc64-prefetch.ll test
+; RUN: llc -mtriple=powerpc64-unknown-linux-gnu -mcpu=pwr8 < %s | FileCheck %s
+
+declare void @llvm.prefetch(i8*, i32, i32, i32)
+
+define void @test(i8* %a, ...) nounwind {
+entry:
+  call void @llvm.prefetch(i8* %a, i32 0, i32 3, i32 0)
+  ret void
+
+; CHECK-LABEL: @test
+; CHECK: icbt
+}
+
+