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 --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index ad37f84fe06341ef52756a886cc51ba9347a2c53..962f8c82b48acd485e4c707ea091d3774c1375b2 100644 (file)
--- 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 7a079072e19d27f9616501ca974e65740dc72662..fce0b3564a8fd66eaf0f635793b9ca94f541d15d 100644 (file)
--- 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 eb3ab8002642999ea2786cf1caf5aa3d88247909..8c3c1b41e794d18a15119a76fdb833554e445846 100644 (file)
--- 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.  */