[PATCH] D76398: [X86] Limit prefix padding w/target specific padding amount

[Kan Shengchen via Phabricator via llvm-commits]

skan added inline comments.


================
Comment at: llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp:865
+  const unsigned TargetPrefixMax =
+    std::min(maximumPrefixPadding(STI), (unsigned)X86PadMaxPrefixSize);
+ 
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Use a C++ style cast here.


================
Comment at: llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp:865
+  const unsigned TargetPrefixMax =
+    std::min(maximumPrefixPadding(STI), (unsigned)X86PadMaxPrefixSize);
+ 
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skan wrote:
> Use a C++ style cast here.
Since the bug fix patch D76285 was landed,  I think we can allow all targets to decide how many prefixes can be added by default,
and user can pass option -x86-pad-max-prefix-size to override the default value.


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Comment at: llvm/test/MC/X86/prefix-padding-length.s:11
+# RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -x86-pad-max-prefix-size=15 -mcpu=skx | llvm-objdump -d --section=.text - | FileCheck %s --check-prefix=CHECK64-PREFIX15
+# RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -x86-pad-max-prefix-size=15 -mcpu=atom | llvm-objdump -d --section=.text - | FileCheck %s --check-prefix=CHECK64-PREFIX2
+# RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -x86-pad-max-prefix-size=15 -mcpu=silvermont | llvm-objdump -d --section=.text - | FileCheck %s --check-prefix=CHECK64-PREFIX0
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>From my knowledge, atom can decode 5 prefixes without penalty.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D76398/new/

https://reviews.llvm.org/D76398