[gcc r12-9087] Disable gather/scatter for zen4

[gcc r12-9087] Disable gather/scatter for zen4

[Jan Hubicka]

https://gcc.gnu.org/g:7790d4b2e5c6ed0d4957e3b7948e24023447fbfd

commit r12-9087-g7790d4b2e5c6ed0d4957e3b7948e24023447fbfd
Author: Jan Hubicka <jh@suse.cz>
Date:   Mon Jan 16 15:40:45 2023 +0100

    Disable gather/scatter for zen4
    
    this patch adds more tunes for zen4:
     - new tunes for avx512 scater instructions.
       In micro benchmarks these seems consistent loss compared to open-coded coe
     - disable use of gather for zen4
       While these are win for a micro benchmarks (based on TSVC), enabling gather
       is a loss for parest. So for now it seems safe to keep it off.
     - disable pass to avoid FMA chains for znver4 since fmadd was optimized and does not seem
       to cause regressions.
    
            * config/i386/i386.cc (ix86_vectorize_builtin_scatter): Guard scatter
            by TARGET_USE_SCATTER.
            * config/i386/i386.h (TARGET_USE_SCATTER_2PARTS,
            TARGET_USE_SCATTER_4PARTS, TARGET_USE_SCATTER): New macros.
            * config/i386/x86-tune.def (TARGET_USE_SCATTER_2PARTS,
            TARGET_USE_SCATTER_4PARTS, TARGET_USE_SCATTER): New tunes.
            (X86_TUNE_AVOID_256FMA_CHAINS, X86_TUNE_AVOID_512FMA_CHAINS): Disable
            for znver4.  (X86_TUNE_USE_GATHER): Disable for zen4.
    
    (cherry picked from commit 967592488c64a86f37bef3dabebb56364f14acdd)

Diff:
---
 gcc/config/i386/i386.cc      |  7 +++++++
 gcc/config/i386/i386.h       |  6 ++++++
 gcc/config/i386/x86-tune.def | 23 +++++++++++++++++++----
 3 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index ad37f84fe06..962f8c82b48 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -18918,6 +18918,13 @@ ix86_vectorize_builtin_scatter (const_tree vectype,
   if (!TARGET_AVX512F)
     return NULL_TREE;
 
+  if (known_eq (TYPE_VECTOR_SUBPARTS (vectype), 2u)
+      ? !TARGET_USE_SCATTER_2PARTS
+      : (known_eq (TYPE_VECTOR_SUBPARTS (vectype), 4u)
+	 ? !TARGET_USE_SCATTER_4PARTS
+	 : !TARGET_USE_SCATTER))
+    return NULL_TREE;
+
   if ((TREE_CODE (index_type) != INTEGER_TYPE
        && !POINTER_TYPE_P (index_type))
       || (TYPE_MODE (index_type) != SImode
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index 7a079072e19..fce0b3564a8 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -392,10 +392,16 @@ extern unsigned char ix86_tune_features[X86_TUNE_LAST];
 	ix86_tune_features[X86_TUNE_AVOID_4BYTE_PREFIXES]
 #define TARGET_USE_GATHER_2PARTS \
 	ix86_tune_features[X86_TUNE_USE_GATHER_2PARTS]
+#define TARGET_USE_SCATTER_2PARTS \
+	ix86_tune_features[X86_TUNE_USE_SCATTER_2PARTS]
 #define TARGET_USE_GATHER_4PARTS \
 	ix86_tune_features[X86_TUNE_USE_GATHER_4PARTS]
+#define TARGET_USE_SCATTER_4PARTS \
+	ix86_tune_features[X86_TUNE_USE_SCATTER_4PARTS]
 #define TARGET_USE_GATHER \
 	ix86_tune_features[X86_TUNE_USE_GATHER]
+#define TARGET_USE_SCATTER \
+	ix86_tune_features[X86_TUNE_USE_SCATTER]
 #define TARGET_FUSE_CMP_AND_BRANCH_32 \
 	ix86_tune_features[X86_TUNE_FUSE_CMP_AND_BRANCH_32]
 #define TARGET_FUSE_CMP_AND_BRANCH_64 \
diff --git a/gcc/config/i386/x86-tune.def b/gcc/config/i386/x86-tune.def
index eb3ab800264..8c3c1b41e79 100644
--- a/gcc/config/i386/x86-tune.def
+++ b/gcc/config/i386/x86-tune.def
@@ -469,28 +469,43 @@ DEF_TUNE (X86_TUNE_AVOID_4BYTE_PREFIXES, "avoid_4byte_prefixes",
 DEF_TUNE (X86_TUNE_USE_GATHER_2PARTS, "use_gather_2parts",
 	  ~(m_ZNVER1 | m_ZNVER2 | m_ZNVER3 | m_ZNVER4 | m_ALDERLAKE | m_GENERIC))
 
+/* X86_TUNE_USE_SCATTER_2PARTS: Use scater instructions for vectors with 2
+   elements.  */
+DEF_TUNE (X86_TUNE_USE_SCATTER_2PARTS, "use_scatter_2parts",
+	  ~(m_ZNVER4 | m_GENERIC))
+
 /* X86_TUNE_USE_GATHER_4PARTS: Use gather instructions for vectors with 4
    elements.  */
 DEF_TUNE (X86_TUNE_USE_GATHER_4PARTS, "use_gather_4parts",
 	  ~(m_ZNVER1 | m_ZNVER2 | m_ZNVER3 | m_ZNVER4 |  m_ALDERLAKE | m_GENERIC))
 
+/* X86_TUNE_USE_SCATTER_4PARTS: Use scater instructions for vectors with 4
+   elements.  */
+DEF_TUNE (X86_TUNE_USE_SCATTER_4PARTS, "use_scatter_4parts",
+	  ~(m_ZNVER4 | m_GENERIC))
+
 /* X86_TUNE_USE_GATHER: Use gather instructions for vectors with 8 or more
    elements.  */
 DEF_TUNE (X86_TUNE_USE_GATHER, "use_gather",
-	  ~(m_ZNVER1 | m_ZNVER2 | m_ALDERLAKE | m_GENERIC))
+	  ~(m_ZNVER1 | m_ZNVER2 | m_ZNVER4 | m_ALDERLAKE | m_GENERIC))
+
+/* X86_TUNE_USE_SCATTER: Use scater instructions for vectors with 8 or more
+   elements.  */
+DEF_TUNE (X86_TUNE_USE_SCATTER, "use_scatter",
+	  ~(m_ZNVER4))
 
 /* X86_TUNE_AVOID_128FMA_CHAINS: Avoid creating loops with tight 128bit or
    smaller FMA chain.  */
-DEF_TUNE (X86_TUNE_AVOID_128FMA_CHAINS, "avoid_fma_chains", m_ZNVER)
+DEF_TUNE (X86_TUNE_AVOID_128FMA_CHAINS, "avoid_fma_chains", m_ZNVER1 | m_ZNVER2 | m_ZNVER3)
 
 /* X86_TUNE_AVOID_256FMA_CHAINS: Avoid creating loops with tight 256bit or
    smaller FMA chain.  */
-DEF_TUNE (X86_TUNE_AVOID_256FMA_CHAINS, "avoid_fma256_chains", m_ZNVER2 | m_ZNVER3 | m_ZNVER4
+DEF_TUNE (X86_TUNE_AVOID_256FMA_CHAINS, "avoid_fma256_chains", m_ZNVER2 | m_ZNVER3
 	  | m_ALDERLAKE | m_SAPPHIRERAPIDS)
 
 /* X86_TUNE_AVOID_512FMA_CHAINS: Avoid creating loops with tight 512bit or
    smaller FMA chain.  */
-DEF_TUNE (X86_TUNE_AVOID_512FMA_CHAINS, "avoid_fma512_chains", m_ZNVER4)
+DEF_TUNE (X86_TUNE_AVOID_512FMA_CHAINS, "avoid_fma512_chains", m_NONE)
 
 /* X86_TUNE_V2DF_REDUCTION_PREFER_PHADDPD: Prefer haddpd
    for v2df vector reduction.  */