gcc 4.8-linaro: backport an upstream fix to fix asm goto miscompilation
Signed-off-by: Felix Fietkau <nbd@openwrt.org> SVN-Revision: 38435
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Felix Fietkau
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1 changed files with 167 additions and 0 deletions
167
toolchain/gcc/patches/4.8-linaro/020-fix_pr58670.patch
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167
toolchain/gcc/patches/4.8-linaro/020-fix_pr58670.patch
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@ -0,0 +1,167 @@
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--- a/gcc/cfgrtl.c
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+++ b/gcc/cfgrtl.c
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@@ -1784,10 +1784,18 @@ commit_one_edge_insertion (edge e)
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}
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/* If the source has one successor and the edge is not abnormal,
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- insert there. Except for the entry block. */
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+ insert there. Except for the entry block.
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+ Don't do this if the predecessor ends in a jump other than
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+ unconditional simple jump. E.g. for asm goto that points all
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+ its labels at the fallthru basic block, we can't insert instructions
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+ before the asm goto, as the asm goto can have various of side effects,
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+ and can't emit instructions after the asm goto, as it must end
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+ the basic block. */
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else if ((e->flags & EDGE_ABNORMAL) == 0
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&& single_succ_p (e->src)
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- && e->src != ENTRY_BLOCK_PTR)
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+ && e->src != ENTRY_BLOCK_PTR
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+ && (!JUMP_P (BB_END (e->src))
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+ || simplejump_p (BB_END (e->src))))
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{
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bb = e->src;
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--- a/gcc/stmt.c
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+++ b/gcc/stmt.c
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@@ -613,6 +613,9 @@ tree_conflicts_with_clobbers_p (tree t,
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CLOBBERS is a list of STRING_CST nodes each naming a hard register
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that is clobbered by this insn.
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+ LABELS is a list of labels, and if LABELS is non-NULL, FALLTHRU_BB
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+ should be the fallthru basic block of the asm goto.
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+
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Not all kinds of lvalue that may appear in OUTPUTS can be stored directly.
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Some elements of OUTPUTS may be replaced with trees representing temporary
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values. The caller should copy those temporary values to the originally
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@@ -622,7 +625,8 @@ tree_conflicts_with_clobbers_p (tree t,
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static void
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expand_asm_operands (tree string, tree outputs, tree inputs,
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- tree clobbers, tree labels, int vol, location_t locus)
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+ tree clobbers, tree labels, basic_block fallthru_bb,
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+ int vol, location_t locus)
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{
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rtvec argvec, constraintvec, labelvec;
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rtx body;
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@@ -643,6 +647,7 @@ expand_asm_operands (tree string, tree o
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enum machine_mode *inout_mode = XALLOCAVEC (enum machine_mode, noutputs);
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const char **constraints = XALLOCAVEC (const char *, noutputs + ninputs);
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int old_generating_concat_p = generating_concat_p;
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+ rtx fallthru_label = NULL_RTX;
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/* An ASM with no outputs needs to be treated as volatile, for now. */
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if (noutputs == 0)
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@@ -942,8 +947,24 @@ expand_asm_operands (tree string, tree o
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/* Copy labels to the vector. */
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for (i = 0, tail = labels; i < nlabels; ++i, tail = TREE_CHAIN (tail))
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- ASM_OPERANDS_LABEL (body, i)
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- = gen_rtx_LABEL_REF (Pmode, label_rtx (TREE_VALUE (tail)));
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+ {
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+ rtx r;
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+ /* If asm goto has any labels in the fallthru basic block, use
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+ a label that we emit immediately after the asm goto. Expansion
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+ may insert further instructions into the same basic block after
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+ asm goto and if we don't do this, insertion of instructions on
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+ the fallthru edge might misbehave. See PR58670. */
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+ if (fallthru_bb
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+ && label_to_block_fn (cfun, TREE_VALUE (tail)) == fallthru_bb)
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+ {
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+ if (fallthru_label == NULL_RTX)
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+ fallthru_label = gen_label_rtx ();
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+ r = fallthru_label;
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+ }
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+ else
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+ r = label_rtx (TREE_VALUE (tail));
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+ ASM_OPERANDS_LABEL (body, i) = gen_rtx_LABEL_REF (Pmode, r);
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+ }
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generating_concat_p = old_generating_concat_p;
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@@ -1067,6 +1088,9 @@ expand_asm_operands (tree string, tree o
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emit_insn (body);
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}
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+ if (fallthru_label)
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+ emit_label (fallthru_label);
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+
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/* For any outputs that needed reloading into registers, spill them
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back to where they belong. */
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for (i = 0; i < noutputs; ++i)
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@@ -1087,6 +1111,7 @@ expand_asm_stmt (gimple stmt)
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const char *s;
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tree str, out, in, cl, labels;
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location_t locus = gimple_location (stmt);
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+ basic_block fallthru_bb = NULL;
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/* Meh... convert the gimple asm operands into real tree lists.
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Eventually we should make all routines work on the vectors instead
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@@ -1122,6 +1147,9 @@ expand_asm_stmt (gimple stmt)
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n = gimple_asm_nlabels (stmt);
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if (n > 0)
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{
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+ edge fallthru = find_fallthru_edge (gimple_bb (stmt)->succs);
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+ if (fallthru)
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+ fallthru_bb = fallthru->dest;
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t = labels = gimple_asm_label_op (stmt, 0);
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for (i = 1; i < n; i++)
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t = TREE_CHAIN (t) = gimple_asm_label_op (stmt, i);
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@@ -1147,7 +1175,7 @@ expand_asm_stmt (gimple stmt)
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/* Generate the ASM_OPERANDS insn; store into the TREE_VALUEs of
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OUTPUTS some trees for where the values were actually stored. */
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- expand_asm_operands (str, outputs, in, cl, labels,
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+ expand_asm_operands (str, outputs, in, cl, labels, fallthru_bb,
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gimple_asm_volatile_p (stmt), locus);
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/* Copy all the intermediate outputs into the specified outputs. */
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--- /dev/null
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+++ b/gcc/testsuite/gcc.dg/torture/pr58670.c
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@@ -0,0 +1,47 @@
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+/* PR middle-end/58670 */
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+/* { dg-do run { target i?86-*-* x86_64-*-* } } */
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+
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+#if defined (__i386__) || defined (__x86_64__)
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+#define ASM_STR "bts $1, %0; jc %l[lab]"
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+#endif
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+
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+__attribute__((noinline, noclone)) int
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+foo (int a, int b)
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+{
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+ if (a)
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+ return -3;
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+#ifdef ASM_STR
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+ asm volatile goto (ASM_STR : : "m" (b) : "memory" : lab);
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+ return 0;
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+lab:
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+#endif
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+ return 0;
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+}
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+
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+int
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+bar (int a, int b)
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+{
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+ if (a)
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+ return -3;
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+#ifdef ASM_STR
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+ asm volatile goto (ASM_STR : : "m" (b) : "memory" : lab);
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+ return 0;
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+lab:
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+#endif
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+ return 0;
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+}
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+
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+int
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+main ()
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+{
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+ if (foo (1, 0) != -3
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+ || foo (0, 3) != 0
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+ || foo (1, 0) != -3
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+ || foo (0, 0) != 0
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+ || bar (1, 0) != -3
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+ || bar (0, 3) != 0
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+ || bar (1, 0) != -3
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+ || bar (0, 0) != 0)
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+ __builtin_abort ();
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+ return 0;
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+}
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