[PULL 18/34] target/arm: Use SVEContLdSt in sve_ld1_r

[Peter Maydell]

From: Richard Henderson <address@hidden>

First use of the new helper functions, so we can remove the
unused markup.  No longer need a scratch for user-only, as
we completely probe the page set before reading; system mode
still requires a scratch for MMIO.

Reviewed-by: Peter Maydell <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
Message-id: address@hidden
Signed-off-by: Peter Maydell <address@hidden>
---
 target/arm/sve_helper.c | 188 +++++++++++++++++++++-------------------
 1 file changed, 97 insertions(+), 91 deletions(-)

diff --git a/target/arm/sve_helper.c b/target/arm/sve_helper.c
index d0071377351..6bae342a177 100644
--- a/target/arm/sve_helper.c
+++ b/target/arm/sve_helper.c
@@ -4221,9 +4221,9 @@ typedef struct {
  * final element on each page.  Identify any single element that spans
  * the page boundary.  Return true if there are any active elements.
  */
-static bool __attribute__((unused))
-sve_cont_ldst_elements(SVEContLdSt *info, target_ulong addr, uint64_t *vg,
-                       intptr_t reg_max, int esz, int msize)
+static bool sve_cont_ldst_elements(SVEContLdSt *info, target_ulong addr,
+                                   uint64_t *vg, intptr_t reg_max,
+                                   int esz, int msize)
 {
     const int esize = 1 << esz;
     const uint64_t pg_mask = pred_esz_masks[esz];
@@ -4313,10 +4313,9 @@ sve_cont_ldst_elements(SVEContLdSt *info, target_ulong 
addr, uint64_t *vg,
  * Control the generation of page faults with @fault.  Return false if
  * there is no work to do, which can only happen with @fault == FAULT_NO.
  */
-static bool __attribute__((unused))
-sve_cont_ldst_pages(SVEContLdSt *info, SVEContFault fault, CPUARMState *env,
-                    target_ulong addr, MMUAccessType access_type,
-                    uintptr_t retaddr)
+static bool sve_cont_ldst_pages(SVEContLdSt *info, SVEContFault fault,
+                                CPUARMState *env, target_ulong addr,
+                                MMUAccessType access_type, uintptr_t retaddr)
 {
     int mmu_idx = cpu_mmu_index(env, false);
     int mem_off = info->mem_off_first[0];
@@ -4388,109 +4387,116 @@ static inline bool test_host_page(void *host)
 /*
  * Common helper for all contiguous one-register predicated loads.
  */
-static void sve_ld1_r(CPUARMState *env, void *vg, const target_ulong addr,
-                      uint32_t desc, const uintptr_t retaddr,
-                      const int esz, const int msz,
-                      sve_ldst1_host_fn *host_fn,
-                      sve_ldst1_tlb_fn *tlb_fn)
+static inline QEMU_ALWAYS_INLINE
+void sve_ld1_r(CPUARMState *env, uint64_t *vg, const target_ulong addr,
+               uint32_t desc, const uintptr_t retaddr,
+               const int esz, const int msz,
+               sve_ldst1_host_fn *host_fn,
+               sve_ldst1_tlb_fn *tlb_fn)
 {
-    const TCGMemOpIdx oi = extract32(desc, SIMD_DATA_SHIFT, MEMOPIDX_SHIFT);
-    const int mmu_idx = get_mmuidx(oi);
     const unsigned rd = extract32(desc, SIMD_DATA_SHIFT + MEMOPIDX_SHIFT, 5);
     void *vd = &env->vfp.zregs[rd];
-    const int diffsz = esz - msz;
     const intptr_t reg_max = simd_oprsz(desc);
-    const intptr_t mem_max = reg_max >> diffsz;
-    ARMVectorReg scratch;
+    intptr_t reg_off, reg_last, mem_off;
+    SVEContLdSt info;
     void *host;
-    intptr_t split, reg_off, mem_off;
+    int flags;
 
-    /* Find the first active element.  */
-    reg_off = find_next_active(vg, 0, reg_max, esz);
-    if (unlikely(reg_off == reg_max)) {
+    /* Find the active elements.  */
+    if (!sve_cont_ldst_elements(&info, addr, vg, reg_max, esz, 1 << msz)) {
         /* The entire predicate was false; no load occurs.  */
         memset(vd, 0, reg_max);
         return;
     }
-    mem_off = reg_off >> diffsz;
 
-    /*
-     * If the (remaining) load is entirely within a single page, then:
-     * For softmmu, and the tlb hits, then no faults will occur;
-     * For user-only, either the first load will fault or none will.
-     * We can thus perform the load directly to the destination and
-     * Vd will be unmodified on any exception path.
-     */
-    split = max_for_page(addr, mem_off, mem_max);
-    if (likely(split == mem_max)) {
-        host = tlb_vaddr_to_host(env, addr + mem_off, MMU_DATA_LOAD, mmu_idx);
-        if (test_host_page(host)) {
-            intptr_t i = reg_off;
-            host -= mem_off;
-            do {
-                host_fn(vd, i, host + (i >> diffsz));
-                i = find_next_active(vg, i + (1 << esz), reg_max, esz);
-            } while (i < reg_max);
-            /* After having taken any fault, zero leading inactive elements. */
-            swap_memzero(vd, reg_off);
-            return;
-        }
-    }
+    /* Probe the page(s).  Exit with exception for any invalid page. */
+    sve_cont_ldst_pages(&info, FAULT_ALL, env, addr, MMU_DATA_LOAD, retaddr);
 
-    /*
-     * Perform the predicated read into a temporary, thus ensuring
-     * if the load of the last element faults, Vd is not modified.
-     */
+    flags = info.page[0].flags | info.page[1].flags;
+    if (unlikely(flags != 0)) {
 #ifdef CONFIG_USER_ONLY
-    swap_memzero(&scratch, reg_off);
-    host = g2h(addr);
-    do {
-        host_fn(&scratch, reg_off, host + (reg_off >> diffsz));
-        reg_off += 1 << esz;
-        reg_off = find_next_active(vg, reg_off, reg_max, esz);
-    } while (reg_off < reg_max);
+        g_assert_not_reached();
 #else
-    memset(&scratch, 0, reg_max);
-    goto start;
-    while (1) {
-        reg_off = find_next_active(vg, reg_off, reg_max, esz);
-        if (reg_off >= reg_max) {
-            break;
-        }
-        mem_off = reg_off >> diffsz;
-        split = max_for_page(addr, mem_off, mem_max);
+        /*
+         * At least one page includes MMIO (or watchpoints).
+         * Any bus operation can fail with cpu_transaction_failed,
+         * which for ARM will raise SyncExternal.  Perform the load
+         * into scratch memory to preserve register state until the end.
+         */
+        ARMVectorReg scratch;
 
-    start:
-        if (split - mem_off >= (1 << msz)) {
-            /* At least one whole element on this page.  */
-            host = tlb_vaddr_to_host(env, addr + mem_off,
-                                     MMU_DATA_LOAD, mmu_idx);
-            if (host) {
-                host -= mem_off;
-                do {
-                    host_fn(&scratch, reg_off, host + mem_off);
-                    reg_off += 1 << esz;
-                    reg_off = find_next_active(vg, reg_off, reg_max, esz);
-                    mem_off = reg_off >> diffsz;
-                } while (split - mem_off >= (1 << msz));
-                continue;
+        memset(&scratch, 0, reg_max);
+        mem_off = info.mem_off_first[0];
+        reg_off = info.reg_off_first[0];
+        reg_last = info.reg_off_last[1];
+        if (reg_last < 0) {
+            reg_last = info.reg_off_split;
+            if (reg_last < 0) {
+                reg_last = info.reg_off_last[0];
             }
         }
 
-        /*
-         * Perform one normal read.  This may fault, longjmping out to the
-         * main loop in order to raise an exception.  It may succeed, and
-         * as a side-effect load the TLB entry for the next round.  Finally,
-         * in the extremely unlikely case we're performing this operation
-         * on I/O memory, it may succeed but not bring in the TLB entry.
-         * But even then we have still made forward progress.
-         */
-        tlb_fn(env, &scratch, reg_off, addr + mem_off, retaddr);
-        reg_off += 1 << esz;
-    }
-#endif
+        do {
+            uint64_t pg = vg[reg_off >> 6];
+            do {
+                if ((pg >> (reg_off & 63)) & 1) {
+                    tlb_fn(env, &scratch, reg_off, addr + mem_off, retaddr);
+                }
+                reg_off += 1 << esz;
+                mem_off += 1 << msz;
+            } while (reg_off & 63);
+        } while (reg_off <= reg_last);
 
-    memcpy(vd, &scratch, reg_max);
+        memcpy(vd, &scratch, reg_max);
+        return;
+#endif
+    }
+
+    /* The entire operation is in RAM, on valid pages. */
+
+    memset(vd, 0, reg_max);
+    mem_off = info.mem_off_first[0];
+    reg_off = info.reg_off_first[0];
+    reg_last = info.reg_off_last[0];
+    host = info.page[0].host;
+
+    while (reg_off <= reg_last) {
+        uint64_t pg = vg[reg_off >> 6];
+        do {
+            if ((pg >> (reg_off & 63)) & 1) {
+                host_fn(vd, reg_off, host + mem_off);
+            }
+            reg_off += 1 << esz;
+            mem_off += 1 << msz;
+        } while (reg_off <= reg_last && (reg_off & 63));
+    }
+
+    /*
+     * Use the slow path to manage the cross-page misalignment.
+     * But we know this is RAM and cannot trap.
+     */
+    mem_off = info.mem_off_split;
+    if (unlikely(mem_off >= 0)) {
+        tlb_fn(env, vd, info.reg_off_split, addr + mem_off, retaddr);
+    }
+
+    mem_off = info.mem_off_first[1];
+    if (unlikely(mem_off >= 0)) {
+        reg_off = info.reg_off_first[1];
+        reg_last = info.reg_off_last[1];
+        host = info.page[1].host;
+
+        do {
+            uint64_t pg = vg[reg_off >> 6];
+            do {
+                if ((pg >> (reg_off & 63)) & 1) {
+                    host_fn(vd, reg_off, host + mem_off);
+                }
+                reg_off += 1 << esz;
+                mem_off += 1 << msz;
+            } while (reg_off & 63);
+        } while (reg_off <= reg_last);
+    }
 }
 
 #define DO_LD1_1(NAME, ESZ) \
-- 
2.20.1