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authorBjörn Gustavsson <[email protected]>2012-03-30 11:05:16 +0200
committerBjörn Gustavsson <[email protected]>2015-07-03 14:28:03 +0200
commit45f469ca089096c8a59ca53d948d05d1a998386e (patch)
tree2da989257d20ae659c7ad8a503d4978e4b6b7a3f /erts
parent54189af4a519b72883dde3263135baf6aba0f81f (diff)
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Change the meaning of 'x' in a transformation
The purpose of this series of commits is to improve code generation for the Clang compiler. As a first step we want to change the meaning of 'x' in a transformation such as: operation Literal=q => move Literal x | operation x Currently, a plain 'x' means reg[0] or x(0), which is the first element in the X register array. That element is distinct from r(0) which is a variable in process_main(). Therefore, since r(0) and x(0) are currently distinct it is fine to use x(0) as a scratch register. However, in the next commit we will eliminate the separate variable for storing the contents of X register zero (thus, x(0) and r(0) will point to the same location in the X register array). Therefore, we must use another scratch register in transformation. Redefine a plain 'x' in a transformation to mean x(1023). Also define SCRATCH_X_REG so that we can refer to the register by name from C code.
Diffstat (limited to 'erts')
-rw-r--r--erts/emulator/beam/beam_load.c2
-rwxr-xr-xerts/emulator/utils/beam_makeops9
2 files changed, 5 insertions, 6 deletions
diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index 10baab506a..f5f1147261 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -4322,7 +4322,7 @@ gen_has_map_fields(LoaderState* stp, GenOpArg Fail, GenOpArg Src,
for (i = 0; i < n; i++) {
op->a[3+2*i] = Rest[i];
op->a[3+2*i+1].type = TAG_x;
- op->a[3+2*i+1].val = 0; /* x(0); normally not used */
+ op->a[3+2*i+1].val = SCRATCH_X_REG; /* Ignore result */
}
return op;
}
diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops
index 7c94546ea4..6e1741af85 100755
--- a/erts/emulator/utils/beam_makeops
+++ b/erts/emulator/utils/beam_makeops
@@ -601,6 +601,7 @@ sub emulator_output {
print "#define MAX_GENERIC_OPCODE ", $num_file_opcodes-1, "\n";
print "#define NUM_GENERIC_OPS ", scalar(@gen_opname), "\n";
print "#define NUM_SPECIFIC_OPS ", scalar(@op_to_name), "\n";
+ print "#define SCRATCH_X_REG 1023\n";
print "\n";
print "#ifdef ARCH_64\n";
print "# define BEAM_WIDE_MASK 0xFFFFUL\n";
@@ -1341,7 +1342,10 @@ sub tr_parse_op {
}
# Get an optional value. (In destination.)
+ $type_val = $type eq 'x' ? 1023 : 0;
if (/^=(.*)/) {
+ error("value not allowed in source: $op")
+ if $src;
$type_val = $1;
$_ = '';
}
@@ -1360,11 +1364,6 @@ sub tr_parse_op {
if $var && $type;
}
- # Test that source has no values.
- if ($src) {
- error("value not allowed in source: $op")
- if $type_val;
- }
($var,$type,$type_val,$cond,$cond_val);
}