bpf: use xBPF signed div, mod insns when available

The 'mod' and 'div' operators in eBPF are unsigned, with no signed
counterpart. xBPF adds two new ALU operations, sdiv and smod, for
signed division and modulus, respectively. Update bpf.md with
'define_insn' blocks for signed div and mod to use them when targetting
xBPF, and add new tests to ensure they are used appropriately.

2020-09-17  David Faust  <david.faust@oracle.com>

gcc/
	* config/bpf/bpf.md: Add defines for signed div and mod operators.

gcc/testsuite/
	* gcc.target/bpf/diag-sdiv.c: New test.
	* gcc.target/bpf/diag-smod.c: New test.
	* gcc.target/bpf/xbpf-sdiv-1.c: New test.
	* gcc.target/bpf/xbpf-smod-1.c: New test.

diff --git a/gcc/config/bpf/bpf.md b/gcc/config/bpf/bpf.md
index 769d8ea009691c147e7c37f9bf37b6db637da2c4..8e7cf508ccffed9c28101a8824f258b698af8af8 100644 (file)
--- a/gcc/config/bpf/bpf.md
+++ b/gcc/config/bpf/bpf.md
@@ -165,6 +165,16 @@
   "div<msuffix>\t%0,%2"
   [(set_attr "type" "<mtype>")])
 
+;; However, xBPF does provide a signed division operator, sdiv.
+
+(define_insn "div<AM:mode>3"
+  [(set (match_operand:AM 0 "register_operand" "=r,r")
+        (div:AM (match_operand:AM 1 "register_operand" " 0,0")
+                (match_operand:AM 2 "reg_or_imm_operand" "r,I")))]
+  "TARGET_XBPF"
+  "sdiv<msuffix>\t%0,%2"
+  [(set_attr "type" "<mtype>")])
+
 ;;; Modulus
 
 ;; Note that eBPF doesn't provide instructions for signed integer
@@ -178,6 +188,16 @@
   "mod<msuffix>\t%0,%2"
   [(set_attr "type" "<mtype>")])
 
+;; Again, xBPF provides a signed version, smod.
+
+(define_insn "mod<AM:mode>3"
+  [(set (match_operand:AM 0 "register_operand" "=r,r")
+        (mod:AM (match_operand:AM 1 "register_operand" " 0,0")
+                (match_operand:AM 2 "reg_or_imm_operand" "r,I")))]
+  "TARGET_XBPF"
+  "smod<msuffix>\t%0,%2"
+  [(set_attr "type" "<mtype>")])
+
 ;;; Logical AND
 (define_insn "and<AM:mode>3"
   [(set (match_operand:AM 0 "register_operand" "=r,r")

diff --git a/gcc/testsuite/gcc.target/bpf/diag-sdiv.c b/gcc/testsuite/gcc.target/bpf/diag-sdiv.c
new file mode 100644 (file)
index 0000000..db0c494
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/diag-sdiv.c
@@ -0,0 +1,12 @@
+/* Verify signed division does not produce 'sdiv' insn in eBPF.  */
+/* { dg-do compile } */
+/* { dg-options "-O0" } */
+
+void
+foo ()
+{
+  signed int x = 5;
+  signed int y = 2;
+  signed int z = x / y;
+}
+/* { dg-final { scan-assembler-not "sdiv(32)?\t%r" } } */

diff --git a/gcc/testsuite/gcc.target/bpf/diag-smod.c b/gcc/testsuite/gcc.target/bpf/diag-smod.c
new file mode 100644 (file)
index 0000000..20234ee
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/diag-smod.c
@@ -0,0 +1,12 @@
+/* Verify signed modulo does not produce 'smod' insn in eBPF.  */
+/* { dg-do compile } */
+/* { dg-options "-O0" } */
+
+void
+foo ()
+{
+  signed int x = 5;
+  signed int y = 2;
+  signed int z = x % y;
+}
+/* { dg-final { scan-assembler-not "smod(32)?\t%r" } } */

diff --git a/gcc/testsuite/gcc.target/bpf/xbpf-sdiv-1.c b/gcc/testsuite/gcc.target/bpf/xbpf-sdiv-1.c
new file mode 100644 (file)
index 0000000..f6c5c9e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/xbpf-sdiv-1.c
@@ -0,0 +1,14 @@
+/* Verify that sdiv instruction is used for xBPF. */
+/* { dg-do compile } */
+/* { dg-options "-O0 -mxbpf" } */
+
+void
+foo ()
+{
+  signed int x = 5;
+  signed int y = 2;
+  signed int z = x / y;
+  signed int w = x / 3;
+}
+
+/* { dg-final { scan-assembler "sdiv(32)?\t%r" } } */

diff --git a/gcc/testsuite/gcc.target/bpf/xbpf-smod-1.c b/gcc/testsuite/gcc.target/bpf/xbpf-smod-1.c
new file mode 100644 (file)
index 0000000..b3e5816
--- /dev/null
+++ b/gcc/testsuite/gcc.target/bpf/xbpf-smod-1.c
@@ -0,0 +1,14 @@
+/* Verify that smod instruction is used for xBPF. */
+/* { dg-do compile } */
+/* { dg-options "-O0 -mxbpf" } */
+
+void
+foo ()
+{
+  signed int x = 5;
+  signed int y = 2;
+  signed int z = x % y;
+  signed int w = x % 3;
+}
+
+/* { dg-final { scan-assembler "smod(32)?\t%r" } } */