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145 lines
5.0 KiB
145 lines
5.0 KiB
PR middle-end/83654
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* explow.c (anti_adjust_stack_and_probe_stack_clash): Test a
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non-constant residual for zero at runtime and avoid probing in
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that case. Reorganize code for trailing problem to mirror handling
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of the residual.
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PR middle-end/83654
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* gcc.target/i386/stack-check-18.c: New test.
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* gcc.target/i386/stack-check-19.c: New test.
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diff --git a/gcc/explow.c b/gcc/explow.c
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index b6c56602152..042e71904ec 100644
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--- a/gcc/explow.c
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+++ b/gcc/explow.c
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@@ -1997,11 +1997,27 @@ anti_adjust_stack_and_probe_stack_clash (rtx size)
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if (residual != CONST0_RTX (Pmode))
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{
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+ rtx label = NULL_RTX;
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+ /* RESIDUAL could be zero at runtime and in that case *sp could
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+ hold live data. Furthermore, we do not want to probe into the
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+ red zone.
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+
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+ Go ahead and just guard the probe at *sp on RESIDUAL != 0 at
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+ runtime if RESIDUAL is not a compile time constant. */
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+ if (!CONST_INT_P (residual))
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+ {
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+ label = gen_label_rtx ();
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+ emit_cmp_and_jump_insns (residual, CONST0_RTX (GET_MODE (residual)),
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+ EQ, NULL_RTX, Pmode, 1, label);
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+ }
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+
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rtx x = force_reg (Pmode, plus_constant (Pmode, residual,
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-GET_MODE_SIZE (word_mode)));
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anti_adjust_stack (residual);
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emit_stack_probe (gen_rtx_PLUS (Pmode, stack_pointer_rtx, x));
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emit_insn (gen_blockage ());
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+ if (!CONST_INT_P (residual))
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+ emit_label (label);
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}
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/* Some targets make optimistic assumptions in their prologues about
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@@ -2014,28 +2030,20 @@ anti_adjust_stack_and_probe_stack_clash (rtx size)
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live data. Furthermore, we don't want to probe into the red
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zone.
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- Go ahead and just guard a probe at *sp on SIZE != 0 at runtime
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+ Go ahead and just guard the probe at *sp on SIZE != 0 at runtime
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if SIZE is not a compile time constant. */
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-
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- /* Ideally we would just probe at *sp. However, if SIZE is not
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- a compile-time constant, but is zero at runtime, then *sp
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- might hold live data. So probe at *sp if we know that
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- an allocation was made, otherwise probe into the red zone
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- which is obviously undesirable. */
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- if (CONST_INT_P (size))
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- {
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- emit_stack_probe (stack_pointer_rtx);
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- emit_insn (gen_blockage ());
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- }
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- else
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+ rtx label = NULL_RTX;
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+ if (!CONST_INT_P (size))
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{
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- rtx label = gen_label_rtx ();
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+ label = gen_label_rtx ();
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emit_cmp_and_jump_insns (size, CONST0_RTX (GET_MODE (size)),
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EQ, NULL_RTX, Pmode, 1, label);
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- emit_stack_probe (stack_pointer_rtx);
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- emit_insn (gen_blockage ());
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- emit_label (label);
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}
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+
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+ emit_stack_probe (stack_pointer_rtx);
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+ emit_insn (gen_blockage ());
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+ if (!CONST_INT_P (size))
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+ emit_label (label);
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}
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}
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diff --git a/gcc/testsuite/gcc.target/i386/stack-check-18.c b/gcc/testsuite/gcc.target/i386/stack-check-18.c
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new file mode 100644
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index 00000000000..6dbff4402da
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--- /dev/null
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+++ b/gcc/testsuite/gcc.target/i386/stack-check-18.c
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@@ -0,0 +1,23 @@
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+/* { dg-do compile } */
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+/* { dg-options "-O2 -fstack-clash-protection -mtune=generic -fdump-rtl-expand" } */
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+/* { dg-require-effective-target supports_stack_clash_protection } */
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+
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+int f1 (char *);
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+
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+int
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+f2 (void)
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+{
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+ const int size = 4096;
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+ char buffer[size];
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+ return f1 (buffer);
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+}
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+
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+/* So we want to verify that at expand time that we probed the main
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+ VLA allocation as well as the residuals. Then we want to verify
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+ there was only one probe in the final assembly (implying the
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+ residual probe was optimized away). */
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+/* { dg-final { scan-rtl-dump-times "allocation and probing in loop" 1 "expand" } } */
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+/* { dg-final { scan-rtl-dump-times "allocation and probing residuals" 1 "expand" } } */
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+
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+/* { dg-final { scan-assembler-times "or\[ql\]" 1 } } */
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+
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diff --git a/gcc/testsuite/gcc.target/i386/stack-check-19.c b/gcc/testsuite/gcc.target/i386/stack-check-19.c
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new file mode 100644
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index 00000000000..b92c126d57f
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--- /dev/null
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+++ b/gcc/testsuite/gcc.target/i386/stack-check-19.c
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@@ -0,0 +1,29 @@
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+/* { dg-do compile } */
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+/* { dg-options "-O2 -fstack-clash-protection -mtune=generic -fdump-rtl-expand" } */
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+/* { dg-require-effective-target supports_stack_clash_protection } */
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+
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+int f1 (char *);
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+
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+int
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+f2 (const int size)
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+{
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+ char buffer[size];
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+ return f1 (buffer);
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+}
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+
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+/* So we want to verify that at expand time that we probed the main
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+ VLA allocation as well as the residuals. Then we want to verify
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+ there are two probes in the final assembly code. */
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+/* { dg-final { scan-rtl-dump-times "allocation and probing in loop" 1 "expand" } } */
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+/* { dg-final { scan-rtl-dump-times "allocation and probing residuals" 1 "expand" } } */
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+/* { dg-final { scan-assembler-times "or\[ql\]" 2 } } */
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+
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+/* We also want to verify (indirectly) that the residual probe is
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+ guarded. We do that by checking the number of conditional
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+ branches. There should be 3. One that bypasses the probe loop, one
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+ in the probe loop and one that bypasses the residual probe.
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+
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+ These will all be equality tests. */
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+/* { dg-final { scan-assembler-times "(\?:je|jne)" 3 } } */
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+
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+
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