gdb/record: add support to vmovd and vmovq instructions

This commit adds support to the x86_64 AVX instructions vmovd and vmovq.
The programmers manuals for Intel and AMD describe these 2 instructions
as being almost the same, but my local testing, using gcc 13.2 on Fedora
39, showed several differences and inconsistencies.

The instruction is supposed to always use the 3-byte VEX prefix, but I
could only find 2-byte versions. The instructions aren't differentiated
by the VEX.w bit, but by opcodes and VEX.pp.

This patch adds a test with many different uses for both vmovd and
vmovq. It also updates the test gdb.reverse/step-precsave.exp to
reference the generic "missing avx support" bug open in the bug tracker
(17346), instead of pointing to one that specifically calls out to
vmovd instructions.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=23188
Approved-By: Tom Tromey <tom@tromey.com>

3 files changed, 288 insertions, 1 deletions

diff --git a/gdb/testsuite/gdb.reverse/i386-avx-reverse.c b/gdb/testsuite/gdb.reverse/i386-avx-reverse.c
new file mode 100644
index 0000000..fd1c68a
--- /dev/null
+++ b/gdb/testsuite/gdb.reverse/i386-avx-reverse.c
@@ -0,0 +1,97 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2023 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Architecture tests for intel i386 platform.  */
+
+#include <stdlib.h>
+
+char global_buf0[] = {0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+		      0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f};
+char global_buf1[] = {0, 0, 0, 0, 0, 0, 0, 0,
+		      0, 0, 0, 0, 0, 0, 0, 0};
+char *dyn_buf0;
+char *dyn_buf1;
+
+int
+vmov_test ()
+{
+  char buf0[] = {0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+		 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f};
+  char buf1[] = {0, 0, 0, 0, 0, 0, 0, 0,
+		 0, 0, 0, 0, 0, 0, 0, 0};
+
+  /*start vmov_test.  */
+
+  /* Operations on registers.  */
+  asm volatile ("mov $0, %rcx");
+  asm volatile ("mov $0xbeef, %rax");
+  asm volatile ("vmovd %rax, %xmm0");
+  asm volatile ("vmovd %xmm0, %rcx");
+  asm volatile ("vmovq %xmm0, %xmm15");
+  asm volatile ("vmovq %0, %%xmm15": : "m" (buf1));
+
+  /* Operations based on local buffers.  */
+  asm volatile ("vmovd %0, %%xmm0": : "m"(buf0));
+  asm volatile ("vmovd %%xmm0, %0": "=m"(buf1));
+  asm volatile ("vmovq %0, %%xmm0": : "m"(buf0));
+  asm volatile ("vmovq %%xmm0, %0": "=m"(buf1));
+
+  /* Operations based on global buffers.  */
+  asm volatile ("vmovd %0, %%xmm0": : "m"(global_buf0));
+  asm volatile ("vmovd %%xmm0, %0": "=m"(global_buf1));
+  asm volatile ("vmovq %0, %%xmm0": : "m"(global_buf0));
+  asm volatile ("vmovq %%xmm0, %0": "=m"(global_buf1));
+
+  /* Operations based on dynamic buffers.  */
+  asm volatile ("vmovd %0, %%xmm0": : "m"(*dyn_buf0));
+  asm volatile ("vmovd %%xmm0, %0": "=m"(*dyn_buf1));
+  asm volatile ("vmovq %0, %%xmm0": : "m"(*dyn_buf0));
+  asm volatile ("vmovq %%xmm0, %0": "=m"(*dyn_buf1));
+
+  /* Reset all relevant buffers. */
+  asm volatile ("vmovq %%xmm15, %0": "=m" (buf1));
+  asm volatile ("vmovq %%xmm15, %0": "=m" (global_buf1));
+  asm volatile ("vmovq %%xmm15, %0": "=m" (*dyn_buf1));
+
+  /* Quick test for a different xmm register.  */
+  asm volatile ("vmovd %0, %%xmm15": "=m" (buf0));
+  asm volatile ("vmovd %0, %%xmm15": "=m" (buf1));
+  asm volatile ("vmovq %0, %%xmm15": "=m" (buf0));
+  asm volatile ("vmovq %0, %%xmm15": "=m" (buf1));
+
+  /* We have a return statement to deal with
+     epilogue in different compilers.  */
+  return 0; /* end vmov_test */
+}
+
+int
+main ()
+{
+  dyn_buf0 = (char *) malloc(sizeof(char) * 16);
+  dyn_buf1 = (char *) malloc(sizeof(char) * 16);
+  for (int i =0; i < 16; i++)
+    {
+      dyn_buf0[i] = 0x20 + i;
+      dyn_buf1[i] = 0;
+    }
+  /* Zero relevant xmm registers, se we know what to look for.  */
+  asm volatile ("vmovq %0, %%xmm0": : "m" (global_buf1));
+  asm volatile ("vmovq %0, %%xmm15": : "m" (global_buf1));
+
+  vmov_test ();
+  return 0;	/* end of main */
+}
diff --git a/gdb/testsuite/gdb.reverse/i386-avx-reverse.exp b/gdb/testsuite/gdb.reverse/i386-avx-reverse.exp
new file mode 100644
index 0000000..65e982e
--- /dev/null
+++ b/gdb/testsuite/gdb.reverse/i386-avx-reverse.exp
@@ -0,0 +1,190 @@
+# Copyright 2009-2023 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the gdb testsuite.
+
+#
+# This test tests some i386 general instructions for reverse execution.
+#
+
+require supports_reverse
+
+if {![istarget "*86*-*linux*"]} {
+    verbose "Skipping i386 reverse tests."
+    return
+}
+
+# TODO: this is the case because I used xmm15 all over the test.
+# Some parts of the test require xmm15 to validate some code paths, but
+# that could be done only on 64bit targets and the rest could use xmm7
+# instead.
+if {![istarget "x86_64-*-*"]} {
+    verbose "avx-reverse requires 64 bit targets"
+    return
+}
+
+standard_testfile
+
+# some targets have leading underscores on assembly symbols.
+set additional_flags [gdb_target_symbol_prefix_flags]
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile \
+	 [list debug $additional_flags]]} {
+    return -1
+}
+
+# Shorthand to test reversing through one instruction and
+# testing if a register has the expected value.
+# Prefix, if included, should end with a colon and space.
+
+proc test_one_register {insn register value {prefix ""}} {
+    gdb_test "reverse-step" "$insn.*" \
+	"${prefix}reverse-step from $insn to test register $register"
+
+    gdb_test "info register $register" \
+	"$register.*uint128 = $value.*" \
+	"${prefix}verify $register before $insn"
+}
+
+# Shorthand to test reversing through one instruction and
+# testing if a variable has the expected value.
+# Prefix, if used, should end with a colon and space.
+
+proc test_one_memory {insn mem value {dynamic false} {prefix ""}} {
+    gdb_test "reverse-step" "$insn.*" \
+	"${prefix}reverse-step from $insn to test memory $mem"
+
+    # For the dynamic buffer, we have to cast and dereference the pointer
+    set cast ""
+    if {$dynamic == true} {
+	set cast {(char [32]) *}
+    }
+
+    gdb_test "p/x $cast$mem" \
+	".*$value.*" \
+	"${prefix}verify $mem before $insn"
+
+}
+
+# Record the execution for the whole function, and stop at its end
+# to check if we can correctly reconstruct the state.
+# In the source code, the function must be FUNCTION_test, and
+# at the end, it must have a comment in the form:
+# /* end FUNCTION_test */
+# Returns true if the full function could be recorded, false otherwise.
+proc record_full_function {function} {
+    set end [gdb_get_line_number "end ${function}_test "]
+    set start [gdb_get_line_number "start ${function}_test"]
+    gdb_breakpoint $start temporary
+    gdb_breakpoint $end temporary
+    gdb_continue_to_breakpoint "start ${function}_test"
+
+    if [supports_process_record] {
+	# Activate process record/replay.
+	gdb_test_no_output "record" "${function}: turn on process record"
+    }
+
+    # We return early in gdb_test_multiple because the rest of the
+    # function is aborting recording and cleaning up to put us back in
+    # a known location.
+    gdb_test_multiple "continue" "continue to end of ${function}_test" {
+	-re " end ${function}_test .*\r\n$::gdb_prompt $" {
+	    pass $gdb_test_name
+	    return true
+	}
+	-re " Illegal instruction.*\r\n$::gdb_prompt $" {
+	    fail $gdb_test_name
+	}
+	-re "Process record does not support VEX instruction.*" {
+	    fail $gdb_test_name
+	}
+    }
+
+    gdb_test "record stop" "Process record is stopped.*" \
+	"delete failed record history"
+    # If we didn't exit early, the temporary breakpoint at the end of
+    # the function hasn't been hit yet, so we can just continue.
+    gdb_continue_to_breakpoint "end ${function}_test" ".*end ${function}_test.*"
+
+    return false
+}
+
+runto_main
+
+global hex
+global decimal
+
+# Record all the execution for vmov tests first.
+
+if {[record_full_function "vmov"] == true} {
+    # Now execute backwards, checking all instructions.
+
+    test_one_register "vmovq" "xmm15" "0x3736353433323130" "reg_reset: "
+    test_one_register "vmovq" "xmm15" "0x0"
+    test_one_register "vmovd" "xmm15" "0x33323130" "reg_reset: "
+    test_one_register "vmovd" "xmm15" "0x0"
+
+    with_test_prefix buffer_reset {
+	test_one_memory "vmovq" "dyn_buf1" \
+	    "0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x0" true
+	test_one_memory "vmovq" "global_buf1" \
+	    "0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x0"
+	test_one_memory "vmovq" "buf1" \
+	    "0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x0"
+    }
+
+    with_test_prefix dynamic_buffers {
+	test_one_memory "vmovq" "dyn_buf1" "0x20, 0x21, 0x22, 0x23, 0x0" true
+	test_one_register "vmovq" "xmm0" "0x23222120"
+	test_one_memory "vmovd" "dyn_buf1" "0x0 .repeats 32 times" true
+	test_one_register "vmovd" "xmm0" "0x1716151413121110"
+    }
+
+    with_test_prefix global_buffers {
+	test_one_memory "vmovq" "global_buf1" "0x10, 0x11, 0x12, 0x13, 0x0"
+	test_one_register "vmovq" "xmm0" "0x13121110"
+	test_one_memory "vmovd" "global_buf1" "0x0 .repeats 32 times"
+	test_one_register "vmovd" "xmm0" "0x3736353433323130"
+    }
+
+    with_test_prefix local_buffers {
+	test_one_memory "vmovq" "buf1" "0x30, 0x31, 0x32, 0x33, 0x0"
+	test_one_register "vmovq" "xmm0" "0x33323130"
+	test_one_memory "vmovd" "buf1" "0x0 .repeats 32 times"
+	test_one_register "vmovd" "xmm0" "0xbeef"
+    }
+
+    # regular registers don't have uint128 members, so do it manually.
+    with_test_prefix registers {
+	test_one_register "vmovq" "xmm15" "0xbeef" "reset xmm15: "
+
+	test_one_register "vmovq" "xmm15" "0x0" "xmm0 to xmm15: "
+
+	gdb_test "reverse-step" "vmovd %xmm0, %rcx.*" \
+	    "reverse step to check rcx recording"
+	gdb_test "print/x \$rcx" "= 0x0" "rcx was recorded"
+
+	test_one_register "vmovd" "xmm0" "0x0"
+    }
+
+    # Stop recording to get a clean history.
+    gdb_test "record stop" "Process record is stopped.*" \
+	"delete history for vmov_test"
+} else {
+    untested "could not record vmov_test"
+}
+
+# Move to the end of vmov_test to set up next.
+gdb_test "finish" "Run till exit from.*vmov_test.*" "leaving vmov_test"
diff --git a/gdb/testsuite/gdb.reverse/step-precsave.exp b/gdb/testsuite/gdb.reverse/step-precsave.exp
index 1dc4251..27b417e 100644
--- a/gdb/testsuite/gdb.reverse/step-precsave.exp
+++ b/gdb/testsuite/gdb.reverse/step-precsave.exp
@@ -47,7 +47,7 @@ with_timeout_factor 20 {
 	    pass $gdb_test_name
 	}
 	-re -wrap "Process record does not support VEX instruction.*" {
-	    kfail "record/23188" $gdb_test_name
+	    kfail "record/17346" $gdb_test_name
 	}
 	-re -wrap "Process record does not support instruction 0xfae64 at.*" {
 	    kfail "record/25038" $gdb_test_name