https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97715
--- Comment #22 from qinzhao at gcc dot gnu.org ---
proposed patch:
This change fixes a bug in the i386 backend when adding
-fzero-call-used-regs=all on a target that has no x87
registers.
When there is no x87 registers available, we should not
zero stack registers.
gcc/Changelog:
PR target/97715
* config/i386/i386.c (zero_all_st_registers): Return
earlier when the FPU is disabled.
gcc/testsuite/ChnageLog:
PR target/97715
* gcc.target/i386/zero-scratch-regs-32.c: New test.
---
gcc/config/i386/i386.c | 5 +++++
gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c | 11 +++++++++++
2 files changed, 16 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 6fc6228a26e..789ef727cf8 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -3640,6 +3640,11 @@ zero_all_vector_registers (HARD_REG_SET
need_zeroed_hardregs)
static bool
zero_all_st_registers (HARD_REG_SET need_zeroed_hardregs)
{
+
+ /* If the FPU is disabled, no need to zero all st registers. */
+ if (! (TARGET_80387 || TARGET_FLOAT_RETURNS_IN_80387))
+ return false;
+
unsigned int num_of_st = 0;
for (unsigned int regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
if ((STACK_REGNO_P (regno) || MMX_REGNO_P (regno))
diff --git a/gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c
b/gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c
new file mode 100644
index 00000000000..ca3261fe5ea
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c
@@ -0,0 +1,11 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fzero-call-used-regs=all -mno-80387" } */
+
+int
+foo (int x)
+{
+ return (x + 1);
+}
+
+/* { dg-final { scan-assembler-not "fldz" } } */
+
--
