74 lines
2.1 KiB
Diff
74 lines
2.1 KiB
Diff
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From 95d8a6545bef39f5deff376c60c38e4e3c13c8f5 Mon Sep 17 00:00:00 2001
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From: zhaowenyu <804544223@qq.com>
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Date: Sat, 25 Jun 2022 00:45:24 +0800
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Subject: [PATCH 10/12] [Backport] ira: Fix unnecessary register spill
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Reference: https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=edf95e51e53697f3050f076675c26a4cece17741
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The variables first_moveable_pseudo and last_moveable_pseudo aren't reset after compiling a function,
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which means they leak into the first scheduler pass of the following function. In some cases, this
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can cause an extra spill during register location of the second function.
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---
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gcc/ira.c | 2 ++
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gcc/testsuite/gcc.target/aarch64/nospill.c | 35 ++++++++++++++++++++++
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2 files changed, 37 insertions(+)
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create mode 100644 gcc/testsuite/gcc.target/aarch64/nospill.c
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diff --git a/gcc/ira.c b/gcc/ira.c
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index 681ec2f46..77e4bb988 100644
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--- a/gcc/ira.c
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+++ b/gcc/ira.c
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@@ -5130,6 +5130,8 @@ move_unallocated_pseudos (void)
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INSN_UID (newinsn), i);
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SET_REG_N_REFS (i, 0);
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}
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+
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+ first_moveable_pseudo = last_moveable_pseudo = 0;
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}
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/* If the backend knows where to allocate pseudos for hard
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diff --git a/gcc/testsuite/gcc.target/aarch64/nospill.c b/gcc/testsuite/gcc.target/aarch64/nospill.c
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new file mode 100644
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index 000000000..968a4267e
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--- /dev/null
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+++ b/gcc/testsuite/gcc.target/aarch64/nospill.c
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@@ -0,0 +1,35 @@
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+/* { dg-do compile } */
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+/* { dg-options "-O3" } */
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+
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+/* The pseudo for P is marked as moveable in the IRA pass. */
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+float
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+func_0 (float a, float b, float c)
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+{
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+ float p = c / a;
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+
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+ if (b > 1)
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+ {
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+ b /= p;
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+ if (c > 2)
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+ a /= 3;
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+ }
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+
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+ return b / c * a;
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+}
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+
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+/* If first_moveable_pseudo and last_moveable_pseudo are not reset correctly,
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+ they will carry over and spill the pseudo for Q. */
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+float
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+func_1 (float a, float b, float c)
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+{
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+ float q = a + b;
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+
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+ c *= a / (b + b);
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+ if (a > 0)
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+ c *= q;
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+
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+ return a * b * c;
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+}
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+
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+/* We have plenty of spare registers, so check nothing has been spilled. */
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+/* { dg-final { scan-assembler-not "\tstr\t" } } */
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--
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2.27.0.windows.1
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