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From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-arm@nongnu.org, qemu-devel@nongnu.org
Cc: Richard Henderson <richard.henderson@linaro.org>
Subject: [PATCH v2 09/57] target/arm: Implement MVE LETP insn
Date: Mon, 14 Jun 2021 16:09:19 +0100	[thread overview]
Message-ID: <20210614151007.4545-10-peter.maydell@linaro.org> (raw)
In-Reply-To: <20210614151007.4545-1-peter.maydell@linaro.org>

Implement the MVE LETP insn.  This is like the existing LE loop-end
insn, but it must perform an FPU-enabled check, and on loop-exit it
resets LTPSIZE to 4.

To accommodate the requirement to do something on loop-exit, we drop
the use of condlabel and instead manage both the TB exits manually,
in the same way we already do in trans_WLS().

The other MVE-specific change to the LE insn is that we must raise an
INVSTATE UsageFault insn if LTPSIZE is not 4.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/t32.decode  |   2 +-
 target/arm/translate.c | 104 +++++++++++++++++++++++++++++++++++++----
 2 files changed, 97 insertions(+), 9 deletions(-)

diff --git a/target/arm/t32.decode b/target/arm/t32.decode
index 1b75db50658..0f9326c724b 100644
--- a/target/arm/t32.decode
+++ b/target/arm/t32.decode
@@ -674,7 +674,7 @@ BL               1111 0. .......... 11.1 ............         @branch24
     DLS          1111 0 0000 100     rn:4 1110 0000 0000 0001 size=4
     WLS          1111 0 0000 100     rn:4 1100 . .......... 1 imm=%lob_imm size=4
     {
-      LE         1111 0 0000 0 f:1 0 1111 1100 . .......... 1 imm=%lob_imm
+      LE         1111 0 0000 0 f:1 tp:1 1111 1100 . .......... 1 imm=%lob_imm
       # This is WLSTP
       WLS        1111 0 0000 0 size:2 rn:4 1100 . .......... 1 imm=%lob_imm
     }
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 1ad0e61fac6..a51e882b867 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -8223,25 +8223,113 @@ static bool trans_LE(DisasContext *s, arg_LE *a)
      * any faster.
      */
     TCGv_i32 tmp;
+    TCGLabel *loopend;
+    bool fpu_active;
 
     if (!dc_isar_feature(aa32_lob, s)) {
         return false;
     }
+    if (a->f && a->tp) {
+        return false;
+    }
+    if (s->condexec_mask) {
+        /*
+         * LE in an IT block is CONSTRAINED UNPREDICTABLE;
+         * we choose to UNDEF, because otherwise our use of
+         * gen_goto_tb(1) would clash with the use of TB exit 1
+         * in the dc->condjmp condition-failed codepath in
+         * arm_tr_tb_stop() and we'd get an assertion.
+         */
+        return false;
+    }
+    if (a->tp) {
+        /* LETP */
+        if (!dc_isar_feature(aa32_mve, s)) {
+            return false;
+        }
+        if (!vfp_access_check(s)) {
+            s->eci_handled = true;
+            return true;
+        }
+    }
 
     /* LE/LETP is OK with ECI set and leaves it untouched */
     s->eci_handled = true;
 
-    if (!a->f) {
-        /* Not loop-forever. If LR <= 1 this is the last loop: do nothing. */
-        arm_gen_condlabel(s);
-        tcg_gen_brcondi_i32(TCG_COND_LEU, cpu_R[14], 1, s->condlabel);
-        /* Decrement LR */
-        tmp = load_reg(s, 14);
-        tcg_gen_addi_i32(tmp, tmp, -1);
-        store_reg(s, 14, tmp);
+    /*
+     * With MVE, LTPSIZE might not be 4, and we must emit an INVSTATE
+     * UsageFault exception for the LE insn in that case. Note that we
+     * are not directly checking FPSCR.LTPSIZE but instead check the
+     * pseudocode LTPSIZE() function, which returns 4 if the FPU is
+     * not currently active (ie ActiveFPState() returns false). We
+     * can identify not-active purely from our TB state flags, as the
+     * FPU is active only if:
+     *  the FPU is enabled
+     *  AND lazy state preservation is not active
+     *  AND we do not need a new fp context (this is the ASPEN/FPCA check)
+     *
+     * Usually we don't need to care about this distinction between
+     * LTPSIZE and FPSCR.LTPSIZE, because the code in vfp_access_check()
+     * will either take an exception or clear the conditions that make
+     * the FPU not active. But LE is an unusual case of a non-FP insn
+     * that looks at LTPSIZE.
+     */
+    fpu_active = !s->fp_excp_el && !s->v7m_lspact && !s->v7m_new_fp_ctxt_needed;
+
+    if (!a->tp && dc_isar_feature(aa32_mve, s) && fpu_active) {
+        /* Need to do a runtime check for LTPSIZE != 4 */
+        TCGLabel *skipexc = gen_new_label();
+        tmp = load_cpu_field(v7m.ltpsize);
+        tcg_gen_brcondi_i32(TCG_COND_EQ, tmp, 4, skipexc);
+        tcg_temp_free_i32(tmp);
+        gen_exception_insn(s, s->pc_curr, EXCP_INVSTATE, syn_uncategorized(),
+                           default_exception_el(s));
+        gen_set_label(skipexc);
+    }
+
+    if (a->f) {
+        /* Loop-forever: just jump back to the loop start */
+        gen_jmp(s, read_pc(s) - a->imm);
+        return true;
+    }
+
+    /*
+     * Not loop-forever. If LR <= loop-decrement-value this is the last loop.
+     * For LE, we know at this point that LTPSIZE must be 4 and the
+     * loop decrement value is 1. For LETP we need to calculate the decrement
+     * value from LTPSIZE.
+     */
+    loopend = gen_new_label();
+    if (!a->tp) {
+        tcg_gen_brcondi_i32(TCG_COND_LEU, cpu_R[14], 1, loopend);
+        tcg_gen_addi_i32(cpu_R[14], cpu_R[14], -1);
+    } else {
+        /*
+         * Decrement by 1 << (4 - LTPSIZE). We need to use a TCG local
+         * so that decr stays live after the brcondi.
+         */
+        TCGv_i32 decr = tcg_temp_local_new_i32();
+        TCGv_i32 ltpsize = load_cpu_field(v7m.ltpsize);
+        tcg_gen_sub_i32(decr, tcg_constant_i32(4), ltpsize);
+        tcg_gen_shl_i32(decr, tcg_constant_i32(1), decr);
+        tcg_temp_free_i32(ltpsize);
+
+        tcg_gen_brcond_i32(TCG_COND_LEU, cpu_R[14], decr, loopend);
+
+        tcg_gen_sub_i32(cpu_R[14], cpu_R[14], decr);
+        tcg_temp_free_i32(decr);
     }
     /* Jump back to the loop start */
     gen_jmp(s, read_pc(s) - a->imm);
+
+    gen_set_label(loopend);
+    if (a->tp) {
+        /* Exits from tail-pred loops must reset LTPSIZE to 4 */
+        tmp = tcg_const_i32(4);
+        store_cpu_field(tmp, v7m.ltpsize);
+    }
+    /* End TB, continuing to following insn */
+    gen_jmp_tb(s, s->base.pc_next, 1);
     return true;
 }
 
-- 
2.20.1



  parent reply	other threads:[~2021-06-14 15:15 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-14 15:09 [PATCH v2 00/57] target/arm: First slice of MVE implementation Peter Maydell
2021-06-14 15:09 ` [PATCH v2 01/57] target/arm: Provide and use H8 and H1_8 macros Peter Maydell
2021-06-14 15:09 ` [PATCH v2 02/57] target/arm: Enable FPSCR.QC bit for MVE Peter Maydell
2021-06-14 15:09 ` [PATCH v2 03/57] target/arm: Handle VPR semantics in existing code Peter Maydell
2021-06-14 15:09 ` [PATCH v2 04/57] target/arm: Add handling for PSR.ECI/ICI Peter Maydell
2021-06-14 19:15   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 05/57] target/arm: Let vfp_access_check() handle late NOCP checks Peter Maydell
2021-06-14 15:09 ` [PATCH v2 06/57] target/arm: Implement MVE LCTP Peter Maydell
2021-06-14 15:09 ` [PATCH v2 07/57] target/arm: Implement MVE WLSTP insn Peter Maydell
2021-06-14 19:20   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 08/57] target/arm: Implement MVE DLSTP Peter Maydell
2021-06-14 15:09 ` Peter Maydell [this message]
2021-06-14 15:09 ` [PATCH v2 10/57] target/arm: Add framework for MVE decode Peter Maydell
2021-06-14 15:09 ` [PATCH v2 11/57] target/arm: Implement MVE VLDR/VSTR (non-widening forms) Peter Maydell
2021-06-14 19:29   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 12/57] target/arm: Implement widening/narrowing MVE VLDR/VSTR insns Peter Maydell
2021-06-14 19:39   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 13/57] target/arm: Move expand_pred_b() data to translate.c Peter Maydell
2021-06-14 19:41   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 14/57] target/arm: Implement MVE VCLZ Peter Maydell
2021-06-14 20:00   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 15/57] target/arm: Implement MVE VCLS Peter Maydell
2021-06-14 15:09 ` [PATCH v2 16/57] bitops.h: Provide hswap32(), hswap64(), wswap64() swapping operations Peter Maydell
2021-06-14 15:09 ` [PATCH v2 17/57] target/arm: Implement MVE VREV16, VREV32, VREV64 Peter Maydell
2021-06-14 20:03   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 18/57] target/arm: Implement MVE VMVN (register) Peter Maydell
2021-06-14 15:09 ` [PATCH v2 19/57] target/arm: Implement MVE VABS Peter Maydell
2021-06-14 20:06   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 20/57] target/arm: Implement MVE VNEG Peter Maydell
2021-06-14 15:09 ` [PATCH v2 21/57] tcg: Make gen_dup_i32() public Peter Maydell
2021-06-14 20:12   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 22/57] target/arm: Implement MVE VDUP Peter Maydell
2021-06-14 20:15   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 23/57] target/arm: Implement MVE VAND, VBIC, VORR, VORN, VEOR Peter Maydell
2021-06-14 15:09 ` [PATCH v2 24/57] target/arm: Implement MVE VADD, VSUB, VMUL Peter Maydell
2021-06-14 15:09 ` [PATCH v2 25/57] target/arm: Implement MVE VMULH Peter Maydell
2021-06-14 15:09 ` [PATCH v2 26/57] target/arm: Implement MVE VRMULH Peter Maydell
2021-06-14 15:09 ` [PATCH v2 27/57] target/arm: Implement MVE VMAX, VMIN Peter Maydell
2021-06-14 15:09 ` [PATCH v2 28/57] target/arm: Implement MVE VABD Peter Maydell
2021-06-14 15:09 ` [PATCH v2 29/57] target/arm: Implement MVE VHADD, VHSUB Peter Maydell
2021-06-14 15:09 ` [PATCH v2 30/57] target/arm: Implement MVE VMULL Peter Maydell
2021-06-14 15:09 ` [PATCH v2 31/57] target/arm: Implement MVE VMLALDAV Peter Maydell
2021-06-14 15:09 ` [PATCH v2 32/57] target/arm: Implement MVE VMLSLDAV Peter Maydell
2021-06-14 15:09 ` [PATCH v2 33/57] include/qemu/int128.h: Add function to create Int128 from int64_t Peter Maydell
2021-06-14 15:09 ` [PATCH v2 34/57] target/arm: Implement MVE VRMLALDAVH, VRMLSLDAVH Peter Maydell
2021-06-14 21:27   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 35/57] target/arm: Implement MVE VADD (scalar) Peter Maydell
2021-06-14 21:30   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 36/57] target/arm: Implement MVE VSUB, VMUL (scalar) Peter Maydell
2021-06-14 15:09 ` [PATCH v2 37/57] target/arm: Implement MVE VHADD, VHSUB (scalar) Peter Maydell
2021-06-14 15:09 ` [PATCH v2 38/57] target/arm: Implement MVE VBRSR Peter Maydell
2021-06-14 15:09 ` [PATCH v2 39/57] target/arm: Implement MVE VPST Peter Maydell
2021-06-14 15:09 ` [PATCH v2 40/57] target/arm: Implement MVE VQADD and VQSUB Peter Maydell
2021-06-14 15:09 ` [PATCH v2 41/57] target/arm: Implement MVE VQDMULH and VQRDMULH (scalar) Peter Maydell
2021-06-14 15:09 ` [PATCH v2 42/57] target/arm: Implement MVE VQDMULL scalar Peter Maydell
2021-06-14 15:09 ` [PATCH v2 43/57] target/arm: Implement MVE VQDMULH, VQRDMULH (vector) Peter Maydell
2021-06-14 15:09 ` [PATCH v2 44/57] target/arm: Implement MVE VQADD, VQSUB (vector) Peter Maydell
2021-06-14 15:09 ` [PATCH v2 45/57] target/arm: Implement MVE VQSHL (vector) Peter Maydell
2021-06-14 21:43   ` Richard Henderson
2021-06-14 15:09 ` [PATCH v2 46/57] target/arm: Implement MVE VQRSHL Peter Maydell
2021-06-14 15:09 ` [PATCH v2 47/57] target/arm: Implement MVE VSHL insn Peter Maydell
2021-06-14 15:09 ` [PATCH v2 48/57] target/arm: Implmement MVE VRSHL Peter Maydell
2021-06-14 15:09 ` [PATCH v2 49/57] target/arm: Implement MVE VQDMLADH and VQRDMLADH Peter Maydell
2021-06-14 15:10 ` [PATCH v2 50/57] target/arm: Implement MVE VQDMLSDH and VQRDMLSDH Peter Maydell
2021-06-14 15:10 ` [PATCH v2 51/57] target/arm: Implement MVE VQDMULL (vector) Peter Maydell
2021-06-14 15:10 ` [PATCH v2 52/57] target/arm: Implement MVE VRHADD Peter Maydell
2021-06-14 15:10 ` [PATCH v2 53/57] target/arm: Implement MVE VADC, VSBC Peter Maydell
2021-06-14 21:58   ` Richard Henderson
2021-06-14 15:10 ` [PATCH v2 54/57] target/arm: Implement MVE VCADD Peter Maydell
2021-06-14 15:10 ` [PATCH v2 55/57] target/arm: Implement MVE VHCADD Peter Maydell
2021-06-14 22:01   ` Richard Henderson
2021-06-14 15:10 ` [PATCH v2 56/57] target/arm: Implement MVE VADDV Peter Maydell
2021-06-14 15:10 ` [PATCH v2 57/57] target/arm: Make VMOV scalar <-> gpreg beatwise for MVE Peter Maydell
2021-06-14 22:20 ` [PATCH v2 00/57] target/arm: First slice of MVE implementation no-reply
2021-06-14 22:22 ` Richard Henderson
2021-06-21 16:37   ` Peter Maydell
2021-06-21 17:13     ` Richard Henderson

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