[Qemu-devel] [PATCH 07/28] Correct ppc popcntb logic, implement popcntw and popcntd

[qemu@gibson.dropbear.id.au]

From: David Gibson <dwg@au1.ibm.com>

qemu already includes support for the popcntb instruction introduced
in POWER5 (although it doesn't actually allow you to choose POWER5).

However, the logic is slightly incorrect: it will generate results
truncated to 32-bits when the CPU is in 32-bit mode.  This is not
normal for powerpc - generally arithmetic instructions on a 64-bit
powerpc cpu will generate full 64 bit results, it's just that only the
low 32 bits will be significant for condition codes.

This patch corrects this nit, which actually simplifies the code slightly.

In addition, this patch implements the popcntw and popcntd
instructions added in POWER7, in preparation for allowing POWER7 as an
emulated CPU.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
---
 target-ppc/cpu.h       |    2 +
 target-ppc/helper.h    |    3 +-
 target-ppc/op_helper.c |   55 +++++++++++++++++++++++++++++++++++++++++++----
 target-ppc/translate.c |   20 +++++++++++++----
 4 files changed, 69 insertions(+), 11 deletions(-)

diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 9a7495a..f9ad3b8 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -1507,6 +1507,8 @@ enum {
     PPC_DCRX           = 0x2000000000000000ULL,
     /* user-mode DCR access, implemented in PowerPC 460                      */
     PPC_DCRUX          = 0x4000000000000000ULL,
+    /* popcntw and popcntd instructions                                      */
+    PPC_POPCNTWD       = 0x8000000000000000ULL,
 };
 
 /*****************************************************************************/
diff --git a/target-ppc/helper.h b/target-ppc/helper.h
index 4227897..19c5ebe 100644
--- a/target-ppc/helper.h
+++ b/target-ppc/helper.h
@@ -38,10 +38,11 @@ DEF_HELPER_2(mulldo, i64, i64, i64)
 
 DEF_HELPER_FLAGS_1(cntlzw, TCG_CALL_CONST | TCG_CALL_PURE, tl, tl)
 DEF_HELPER_FLAGS_1(popcntb, TCG_CALL_CONST | TCG_CALL_PURE, tl, tl)
+DEF_HELPER_FLAGS_1(popcntw, TCG_CALL_CONST | TCG_CALL_PURE, tl, tl)
 DEF_HELPER_2(sraw, tl, tl, tl)
 #if defined(TARGET_PPC64)
 DEF_HELPER_FLAGS_1(cntlzd, TCG_CALL_CONST | TCG_CALL_PURE, tl, tl)
-DEF_HELPER_FLAGS_1(popcntb_64, TCG_CALL_CONST | TCG_CALL_PURE, tl, tl)
+DEF_HELPER_FLAGS_1(popcntd, TCG_CALL_CONST | TCG_CALL_PURE, tl, tl)
 DEF_HELPER_2(srad, tl, tl, tl)
 #endif
 
diff --git a/target-ppc/op_helper.c b/target-ppc/op_helper.c
index b9b5ae2..9dd3217 100644
--- a/target-ppc/op_helper.c
+++ b/target-ppc/op_helper.c
@@ -497,6 +497,50 @@ target_ulong helper_srad (target_ulong value, target_ulong shift)
 }
 #endif
 
+#if defined(TARGET_PPC64)
+target_ulong helper_popcntb (target_ulong val)
+{
+    val = (val & 0x5555555555555555ULL) + ((val >>  1) &
+                                           0x5555555555555555ULL);
+    val = (val & 0x3333333333333333ULL) + ((val >>  2) &
+                                           0x3333333333333333ULL);
+    val = (val & 0x0f0f0f0f0f0f0f0fULL) + ((val >>  4) &
+                                           0x0f0f0f0f0f0f0f0fULL);
+    return val;
+}
+
+target_ulong helper_popcntw (target_ulong val)
+{
+    val = (val & 0x5555555555555555ULL) + ((val >>  1) &
+                                           0x5555555555555555ULL);
+    val = (val & 0x3333333333333333ULL) + ((val >>  2) &
+                                           0x3333333333333333ULL);
+    val = (val & 0x0f0f0f0f0f0f0f0fULL) + ((val >>  4) &
+                                           0x0f0f0f0f0f0f0f0fULL);
+    val = (val & 0x00ff00ff00ff00ffULL) + ((val >>  8) &
+                                           0x00ff00ff00ff00ffULL);
+    val = (val & 0x0000ffff0000ffffULL) + ((val >> 16) &
+                                           0x0000ffff0000ffffULL);
+    return val;
+}
+
+target_ulong helper_popcntd (target_ulong val)
+{
+    val = (val & 0x5555555555555555ULL) + ((val >>  1) &
+                                           0x5555555555555555ULL);
+    val = (val & 0x3333333333333333ULL) + ((val >>  2) &
+                                           0x3333333333333333ULL);
+    val = (val & 0x0f0f0f0f0f0f0f0fULL) + ((val >>  4) &
+                                           0x0f0f0f0f0f0f0f0fULL);
+    val = (val & 0x00ff00ff00ff00ffULL) + ((val >>  8) &
+                                           0x00ff00ff00ff00ffULL);
+    val = (val & 0x0000ffff0000ffffULL) + ((val >> 16) &
+                                           0x0000ffff0000ffffULL);
+    val = (val & 0x00000000ffffffffULL) + ((val >> 32) &
+                                           0x00000000ffffffffULL);
+    return val;
+}
+#else
 target_ulong helper_popcntb (target_ulong val)
 {
     val = (val & 0x55555555) + ((val >>  1) & 0x55555555);
@@ -505,12 +549,13 @@ target_ulong helper_popcntb (target_ulong val)
     return val;
 }
 
-#if defined(TARGET_PPC64)
-target_ulong helper_popcntb_64 (target_ulong val)
+target_ulong helper_popcntw (target_ulong val)
 {
-    val = (val & 0x5555555555555555ULL) + ((val >>  1) & 0x5555555555555555ULL);
-    val = (val & 0x3333333333333333ULL) + ((val >>  2) & 0x3333333333333333ULL);
-    val = (val & 0x0f0f0f0f0f0f0f0fULL) + ((val >>  4) & 0x0f0f0f0f0f0f0f0fULL);
+    val = (val & 0x55555555) + ((val >>  1) & 0x55555555);
+    val = (val & 0x33333333) + ((val >>  2) & 0x33333333);
+    val = (val & 0x0f0f0f0f) + ((val >>  4) & 0x0f0f0f0f);
+    val = (val & 0x00ff00ff) + ((val >>  8) & 0x00ff00ff);
+    val = (val & 0x0000ffff) + ((val >> 16) & 0x0000ffff);
     return val;
 }
 #endif
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 2b1a851..5c28ac3 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -1483,13 +1483,21 @@ static void gen_xoris(DisasContext *ctx)
 /* popcntb : PowerPC 2.03 specification */
 static void gen_popcntb(DisasContext *ctx)
 {
+    gen_helper_popcntb(cpu_gpr[rA(ctx->opcode)], cpu_gpr[rS(ctx->opcode)]);
+}
+
+static void gen_popcntw(DisasContext *ctx)
+{
+    gen_helper_popcntw(cpu_gpr[rA(ctx->opcode)], cpu_gpr[rS(ctx->opcode)]);
+}
+
 #if defined(TARGET_PPC64)
-    if (ctx->sf_mode)
-        gen_helper_popcntb_64(cpu_gpr[rA(ctx->opcode)], cpu_gpr[rS(ctx->opcode)]);
-    else
-#endif
-        gen_helper_popcntb(cpu_gpr[rA(ctx->opcode)], cpu_gpr[rS(ctx->opcode)]);
+/* popcntd: PowerPC 2.06 specification */
+static void gen_popcntd(DisasContext *ctx)
+{
+    gen_helper_popcntd(cpu_gpr[rA(ctx->opcode)], cpu_gpr[rS(ctx->opcode)]);
 }
+#endif
 
 #if defined(TARGET_PPC64)
 /* extsw & extsw. */
@@ -8034,7 +8042,9 @@ GEN_HANDLER(oris, 0x19, 0xFF, 0xFF, 0x00000000, PPC_INTEGER),
 GEN_HANDLER(xori, 0x1A, 0xFF, 0xFF, 0x00000000, PPC_INTEGER),
 GEN_HANDLER(xoris, 0x1B, 0xFF, 0xFF, 0x00000000, PPC_INTEGER),
 GEN_HANDLER(popcntb, 0x1F, 0x03, 0x03, 0x0000F801, PPC_POPCNTB),
+GEN_HANDLER(popcntw, 0x1F, 0x1A, 0x0b, 0x0000F801, PPC_POPCNTWD),
 #if defined(TARGET_PPC64)
+GEN_HANDLER(popcntd, 0x1F, 0x1A, 0x0F, 0x0000F801, PPC_POPCNTWD),
 GEN_HANDLER(cntlzd, 0x1F, 0x1A, 0x01, 0x00000000, PPC_64B),
 #endif
 GEN_HANDLER(rlwimi, 0x14, 0xFF, 0xFF, 0x00000000, PPC_INTEGER),
-- 
1.7.1