bcm5719-llvm/llvm/lib/CodeGen/AsmPrinter, branch meklort-10.0.1

[AArch64] -fpatchable-function-entry=N,0: place patch label after BTI

2020-02-03T12:57:25+00:00

Summary: For -fpatchable-function-entry=N,0 -mbranch-protection=bti, after 9a24488cb67a90f889529987275c5e411ce01dda, we place the NOP sled after the initial BTI. ``` .Lfunc_begin0: bti c nop nop .section __patchable_function_entries,"awo",@progbits,f,unique,0 .p2align 3 .xword .Lfunc_begin0 ``` This patch adds a label after the initial BTI and changes the __patchable_function_entries entry to reference the label: ``` .Lfunc_begin0: bti c .Lpatch0: nop nop .section __patchable_function_entries,"awo",@progbits,f,unique,0 .p2align 3 .xword .Lpatch0 ``` This placement is compatible with the resolution in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92424 . A local linkage function whose address is not taken does not need a BTI. Placing the patch label after BTI has the advantage that code does not need to differentiate whether the function has an initial BTI. Reviewers: mrutland, nickdesaulniers, nsz, ostannard Subscribers: kristof.beyls, hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D73680 (cherry picked from commit 06b8e32d4fd3f634f793e3bc0bc4fdb885e7a3ac)

Revert "Reland: [DWARF] Allow cross-CU references of subprogram definitions"

2020-01-29T21:18:16+00:00

... as well as: Revert "[DWARF] Defer creating declaration DIEs until we prepare call site info" This reverts commit fa4701e1979553c2df61698ac1ac212627630442. This reverts commit 79daafc90308787b52a5d3a7586e82acd5e374b3. There have been reports of this assert getting hit: CalleeDIE && "Could not find DIE for call site entry origin (cherry picked from commit 802bec896171997a7b73dde3857712e0eedeabc1)

Add function attribute "patchable-function-prefix" to support -fpatchable-function-entry=N,M where M>0

2020-01-24T18:38:40+00:00

Similar to the function attribute `prefix` (prefix data), "patchable-function-prefix" inserts data (M NOPs) before the function entry label. -fpatchable-function-entry=2,1 (1 NOP before entry, 1 NOP after entry) will look like: ``` .type foo,@function .Ltmp0: # @foo nop foo: .Lfunc_begin0: # optional `bti c` (AArch64 Branch Target Identification) or # `endbr64` (Intel Indirect Branch Tracking) nop .section __patchable_function_entries,"awo",@progbits,get,unique,0 .p2align 3 .quad .Ltmp0 ``` -fpatchable-function-entry=N,0 + -mbranch-protection=bti/-fcf-protection=branch has two reasonable placements (https://gcc.gnu.org/ml/gcc-patches/2020-01/msg01185.html): ``` (a) (b) func: func: .Ltmp0: bti c bti c .Ltmp0: nop nop ``` (a) needs no additional code. If the consensus is to go for (b), we will need more code in AArch64BranchTargets.cpp / X86IndirectBranchTracking.cpp . Differential Revision: https://reviews.llvm.org/D73070 (cherry picked from commit 22467e259507f5ead2a87d989251b4c951a587e4)

[AsmPrinter] Don't emit __patchable_function_entries entry if "patchable-function-entry"="0"

2020-01-24T18:38:40+00:00

Add improve tests (cherry picked from commit d232c215669cb57f5eb4ead40a4a336220dbc429)

Revert "[DWARF5][DebugInfo]: Added support for DebugInfo generation for auto return type for C++ member functions."

2020-01-13T21:58:14+00:00

This reverts commit c958639098a8702b831952b1a1a677ae19190a55, which causes a crash. See https://reviews.llvm.org/D70524 for details.

[DWARF5][DebugInfo]: Added support for DebugInfo generation for auto return type for C++ member functions.

2020-01-13T06:56:13+00:00

Summary: This patch will provide support for auto return type for the C++ member functions. Before this return type of the member function is deduced and stored in the DIE. This patch includes llvm side implementation of this feature. Patch by: Awanish Pandey Reviewers: dblaikie, aprantl, shafik, alok, SouraVX, jini.susan.george Reviewed by: dblaikie Differential Revision: https://reviews.llvm.org/D70524

__patchable_function_entries: don't use linkage field 'unique' with -no-integrated-as

2020-01-12T20:53:44+00:00

.section name, "flags"G, @type, GroupName[, linkage] As of binutils 2.33, linkage cannot be 'unique'. For integrated assembler, we use both 'o' flag and 'unique' linkage to support --gc-sections and COMDAT with lld. https://sourceware.org/ml/binutils/2019-11/msg00266.html

[AArch64] Add function attribute "patchable-function-entry" to add NOPs at function entry

2020-01-10T17:55:51+00:00

The Linux kernel uses -fpatchable-function-entry to implement DYNAMIC_FTRACE_WITH_REGS for arm64 and parisc. GCC 8 implemented -fpatchable-function-entry, which can be seen as a generalized form of -mnop-mcount. The N,M form (function entry points before the Mth NOP) is currently only used by parisc. This patch adds N,0 support to AArch64 codegen. N is represented as the function attribute "patchable-function-entry". We will use a different function attribute for M, if we decide to implement it. The patch reuses the existing patchable-function pass, and TargetOpcode::PATCHABLE_FUNCTION_ENTER which is currently used by XRay. When the integrated assembler is used, __patchable_function_entries will be created for each text section with the SHF_LINK_ORDER flag to prevent --gc-sections (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93197) and COMDAT (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93195) issues. Retrospectively, __patchable_function_entries should use a PC-relative relocation type to avoid the SHF_WRITE flag and dynamic relocations. "patchable-function-entry"'s interaction with Branch Target Identification is still unclear (see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92424 for GCC discussions). Reviewed By: peter.smith Differential Revision: https://reviews.llvm.org/D72215

Don't rely on 'l'(ell) modifiers to indicate a label reference

2020-01-06T22:44:03+00:00

Summary: It's not necessary to use an 'l'(ell) modifier when referencing a label. Treat block addresses and MBB references as if the modifier is used anyway. This prevents us from generating references to ficticious labels. Reviewers: jyknight, nickdesaulniers, hfinkel Subscribers: hiraditya, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D71849

DebugInfo: Correct the form of DW_AT_macro_info in .dwo files (sec_offset, rather than data4)

2019-12-24T09:23:21+00:00