From: Julian Seward <jseward@acm.org>
Date: Sat, 26 Mar 2011 07:30:39 +0000 (+0000)
Subject: Add a test case for non-overwriting of CC_NDEP in shifts by zero.
X-Git-Tag: svn/VALGRIND_3_7_0~567
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b28bc73ed4f764281d48f217060a38ed31d23bfd;p=thirdparty%2Fvalgrind.git

Add a test case for non-overwriting of CC_NDEP in shifts by zero.
See #269354.  (Stephen McCamant, smcc@CS.Berkeley.EDU)


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11667
---

diff --git a/none/tests/x86/Makefile.am b/none/tests/x86/Makefile.am
index 1b8aad5c75..ebdd95d8b4 100644
--- a/none/tests/x86/Makefile.am
+++ b/none/tests/x86/Makefile.am
@@ -54,6 +54,7 @@ EXTRA_DIST = \
 	movx.stderr.exp movx.stdout.exp movx.vgtest \
 	pushpopseg.stderr.exp pushpopseg.stdout.exp pushpopseg.vgtest \
 	sbbmisc.stderr.exp sbbmisc.stdout.exp sbbmisc.vgtest \
+	shift_ndep.stderr.exp shift_ndep.stdout.exp shift_ndep.vgtest \
 	smc1.stderr.exp smc1.stdout.exp smc1.vgtest \
 	ssse3_misaligned.stderr.exp ssse3_misaligned.stdout.exp \
 	ssse3_misaligned.vgtest ssse3_misaligned.c \
@@ -87,6 +88,7 @@ check_PROGRAMS = \
 	movx \
 	pushpopseg \
 	sbbmisc \
+	shift_ndep \
 	smc1 \
 	x86locked \
 	yield \
diff --git a/none/tests/x86/shift_ndep.c b/none/tests/x86/shift_ndep.c
new file mode 100644
index 0000000000..7fc34c982f
--- /dev/null
+++ b/none/tests/x86/shift_ndep.c
@@ -0,0 +1,42 @@
+#include "tests/asm.h"
+#include <stdio.h>
+
+/* Test whether a shift by zero properly preserves the CC_NDEP thunk. */
+
+/* Check whether the carry flag is properly preserved by a variable
+   shift when the shift amount happens to be zero. */
+int shift_ndep( void )
+{
+  char shift_amt = 0;
+  int x = -2;
+  /* First we set the carry flag. Then we increment %x, which sets
+     CC_OP to X86G_CC_OP_INCL and stores the carry (1) in
+     CC_NDEP. Then we left shift %x by a variable amount that happens
+     to be zero, which should leave both %x and all the flags
+     unchanged. Then we add-with-carry 0 to %x, which (assuming the
+     carry is still set as it should be) increments %x again. Thus the
+     expected final value for x is -2 + 1 + 1 = 0.
+
+     If instead the shift clears CC_NDEP (as it would legally do if
+     the shift amount were non-zero), this will be interpeted as
+     clearing the carry bit, so the adc will be a no-op and the final
+     value of %x will instead be -1.
+  */
+  asm (
+       "stc"                    "\n\t"
+       "inc %[x]"               "\n\t"
+       "shl %[shift_amt], %[x]" "\n\t"
+       "adc $0, %[x]"           "\n\t"
+       : [x] "+r" (x) : [shift_amt] "c" (shift_amt));
+  return x;
+}
+
+int main ( void )
+{
+  int r = shift_ndep();
+  if (r == 0)
+    printf("Passed (%d).\n", r);
+  else
+    printf("Failed (%d).\n", r);
+  return 0;
+}
diff --git a/none/tests/x86/shift_ndep.stderr.exp b/none/tests/x86/shift_ndep.stderr.exp
new file mode 100644
index 0000000000..139597f9cb
--- /dev/null
+++ b/none/tests/x86/shift_ndep.stderr.exp
@@ -0,0 +1,2 @@
+
+
diff --git a/none/tests/x86/shift_ndep.stdout.exp b/none/tests/x86/shift_ndep.stdout.exp
new file mode 100644
index 0000000000..9890a0bd79
--- /dev/null
+++ b/none/tests/x86/shift_ndep.stdout.exp
@@ -0,0 +1 @@
+Passed (0).
diff --git a/none/tests/x86/shift_ndep.vgtest b/none/tests/x86/shift_ndep.vgtest
new file mode 100644
index 0000000000..1629604aa2
--- /dev/null
+++ b/none/tests/x86/shift_ndep.vgtest
@@ -0,0 +1 @@
+prog: shift_ndep