gcc: add llvm-gcc and llvm from trunk (does not successfully compile a target yet...

[openwrt.git] / toolchain / gcc / patches / llvm / 904-flatten-switch-stmt-00.patch

diff --git a/toolchain/gcc/patches/llvm/904-flatten-switch-stmt-00.patch b/toolchain/gcc/patches/llvm/904-flatten-switch-stmt-00.patch
new file mode 100644 (file)
index 0000000..f3a6372
--- /dev/null
+++ b/toolchain/gcc/patches/llvm/904-flatten-switch-stmt-00.patch
@@ -0,0 +1,72 @@
+Hi,
+
+The attached patch makes sure that we create smaller object code for
+simple switch statements. We just make sure to flatten the switch
+statement into an if-else chain, basically.
+
+This fixes a size-regression as compared to gcc-3.4, as can be seen
+below.
+
+2007-04-15  Bernhard Fischer  <..>
+
+       * stmt.c (expand_case): Do not create a complex binary tree when
+       optimizing for size but rather use the simple ordered list.
+       (emit_case_nodes): do not emit jumps to the default_label when
+       optimizing for size.
+
+Not regtested so far.
+Comments?
+
+Attached is the test switch.c mentioned below.
+
+$ for i in 2.95 3.3 3.4 4.0 4.1 4.2.orig-HEAD 4.3.orig-HEAD 4.3-HEAD;do
+gcc-$i  -DCHAIN -Os -o switch-CHAIN-$i.o -c switch.c ;done
+$ for i in 2.95 3.3 3.4 4.0 4.1 4.2.orig-HEAD 4.3.orig-HEAD 4.3-HEAD;do
+gcc-$i  -UCHAIN -Os -o switch-$i.o -c switch.c ;done
+
+$ size switch-*.o
+   text           data     bss     dec     hex filename
+    169              0       0     169      a9 switch-2.95.o
+    115              0       0     115      73 switch-3.3.o
+    103              0       0     103      67 switch-3.4.o
+    124              0       0     124      7c switch-4.0.o
+    124              0       0     124      7c switch-4.1.o
+    124              0       0     124      7c switch-4.2.orig-HEAD.o
+     95              0       0      95      5f switch-4.3-HEAD.o
+    124              0       0     124      7c switch-4.3.orig-HEAD.o
+    166              0       0     166      a6 switch-CHAIN-2.95.o
+    111              0       0     111      6f switch-CHAIN-3.3.o
+     95              0       0      95      5f switch-CHAIN-3.4.o
+     95              0       0      95      5f switch-CHAIN-4.0.o
+     95              0       0      95      5f switch-CHAIN-4.1.o
+     95              0       0      95      5f switch-CHAIN-4.2.orig-HEAD.o
+     95              0       0      95      5f switch-CHAIN-4.3-HEAD.o
+     95              0       0      95      5f switch-CHAIN-4.3.orig-HEAD.o
+
+
+Content-Type: text/x-diff; charset=us-ascii
+Content-Disposition: attachment; filename="gcc-4.3.gcc-flatten-switch-stmt.00.diff"
+
+--- a/gcc/stmt.c
++++ b/gcc/stmt.c
+@@ -2574,7 +2574,11 @@ expand_case (tree exp)
+         use_cost_table
+           = (TREE_CODE (orig_type) != ENUMERAL_TYPE
+              && estimate_case_costs (case_list));
+-        balance_case_nodes (&case_list, NULL);
++        /* When optimizing for size, we want a straight list to avoid
++           jumps as much as possible. This basically creates an if-else
++           chain.  */
++        if (!optimize_size)
++          balance_case_nodes (&case_list, NULL);
+         emit_case_nodes (index, case_list, default_label, index_type);
+         emit_jump (default_label);
+       }
+@@ -3136,6 +3140,7 @@ emit_case_nodes (rtx index, case_node_pt
+           {
+             if (!node_has_low_bound (node, index_type))
+               {
++                if (!optimize_size) /* don't jl to the .default_label. */
+                 emit_cmp_and_jump_insns (index,
+                                          convert_modes
+                                          (mode, imode,