AVX-512: dec/inc instructions are slow on KNL

After Alexey Volkov, I'm adding the same property for KNL, that prefers ADD/SUB instead of INC/DEC.
Added a test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212178 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/X86.td b/lib/Target/X86/X86.td
index 0ac801a9b0a0d9163ab532e482a05b49c02682a0..93f516a151a90b8848b977c7b4d2b15aad321f4a 100644 (file)
--- a/lib/Target/X86/X86.td
+++ b/lib/Target/X86/X86.td
@@ -273,7 +273,8 @@ def : ProcessorModel<"knl", HaswellModel,
                       FeatureCMPXCHG16B, FeatureFastUAMem, FeaturePOPCNT,
                       FeatureAES, FeaturePCLMUL, FeatureRDRAND, FeatureF16C,
                       FeatureFSGSBase, FeatureMOVBE, FeatureLZCNT, FeatureBMI,
-                      FeatureBMI2, FeatureFMA, FeatureRTM, FeatureHLE]>;
+                      FeatureBMI2, FeatureFMA, FeatureRTM, FeatureHLE,
+                      FeatureSlowIncDec]>;
 
 def : Proc<"k6",              [FeatureMMX]>;
 def : Proc<"k6-2",            [Feature3DNow]>;

diff --git a/test/CodeGen/X86/avx512-inc-dec.ll b/test/CodeGen/X86/avx512-inc-dec.ll
new file mode 100644 (file)
index 0000000..f04ca87
--- /dev/null
+++ b/test/CodeGen/X86/avx512-inc-dec.ll
@@ -0,0 +1,13 @@
+; RUN: llc < %s -march=x86-64 -mtriple=x86_64-apple-darwin -mcpu=knl | FileCheck %s
+
+;CHECK-LABEL: test
+;CHECK-NOT: dec
+;CHECK_NOT: enc
+;CHECK: ret
+define i32 @test(i32 %a, i32 %b) {
+ %a1 = add i32 %a, -1
+ %b1 = add i32 %b, 1
+ %res = mul i32 %a1, %b1
+ ret i32 %res
+}
+