[AArch64] support .arch_extension dit
#169999
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@llvm/pr-subscribers-backend-aarch64 Author: Folkert de Vries (folkertdev) Changesfixes #146866 The issue discusses that it is unfortunate that command line flag parsing and assembly parsing don't share the infrastructure for recognizing features, which can lead to inconsistencies like here. I don't really see how I can combine them though, so for now this change will fix the immediate problem. Full diff: https://github.com/llvm/llvm-project/pull/169999.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
index 433cb0387c470..7116fd0ea3b6f 100644
--- a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
+++ b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
@@ -3954,6 +3954,7 @@ static const struct Extension {
{"poe2", {AArch64::FeatureS1POE2}},
{"tev", {AArch64::FeatureTEV}},
{"btie", {AArch64::FeatureBTIE}},
+ {"dit", {AArch64::FeatureDIT}},
};
static void setRequiredFeatureString(FeatureBitset FBS, std::string &Str) {
diff --git a/llvm/test/MC/AArch64/directive-arch_extension.s b/llvm/test/MC/AArch64/directive-arch_extension.s
index 3c754077572a1..f174e9d4d187e 100644
--- a/llvm/test/MC/AArch64/directive-arch_extension.s
+++ b/llvm/test/MC/AArch64/directive-arch_extension.s
@@ -197,3 +197,7 @@ fmmla v1.8h, v2.16b, v3.16b
.arch_extension f8f32mm
fmmla v1.4s, v2.16b, v3.16b
// CHECK: fmmla v1.4s, v2.16b, v3.16b
+
+.arch_extension dit
+msr DIT, #1
+// CHECK: msr DIT, #1
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davemgreen
requested review from
davemgreen,
efriedma-quic,
jthackray and
ostannard
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GCC doesn't support this (https://gcc.godbolt.org/z/EcvKh4Tjv), but if there is a -march option then it sounds OK to add one. The other alternative is to remove the need for +dit, like GCC has it. See for example #163166. I believe there is the idea that sys-reg only extensions do not give an error, as you can only write the assembly where you know they are useful. I think either is fine, I'm not sure what others think and whether I've mis-remembered the idea of MSR sysregs. |
efriedma-quic
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efriedma-quic
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I think the set of extensions we support with march should be the same as the list here.
Going through the list, the following are missing:
brbe
bti
fcma
jscvt
pauth-lr
pmuv3
ssve-fexpa
wfxt
Maybe we can do them all in one batch?
I think this is worth fixing regardless of whether we require dit for the asm parser to parse msr DIT.
5 participants
fixes #146866
The issue discusses that it is unfortunate that command line flag parsing and assembly parsing don't share the infrastructure for recognizing features, which can lead to inconsistencies like here. I don't really see how I can combine them though, so for now this change will fix the immediate problem.