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[XRay] ARM 32-bit no-Thumb support in LLVM This is a port of XRay to ARM 32-bit, without Thumb support yet. The XRay instrumentation support is moving up to AsmPrinter. This is one of 3 commits to different repositories of XRay ARM port. The other 2 are: https://reviews.llvm.org/D23932 (Clang test) https://reviews.llvm.org/D23933 (compiler-rt) Differential Revision: https://reviews.llvm.org/D23931 llvm-svn: 281878
2016-09-19 08:54:35 +08:00
; RUN: llc -filetype=asm -o - -mtriple=armv7-unknown-linux-gnu < %s | FileCheck %s
[xray] Add XRay support for Mach-O in CodeGen Currently, XRay only supports emitting the XRay table (xray_instr_map) on ELF binaries. Let's add Mach-O support. Differential Revision: https://reviews.llvm.org/D26983 llvm-svn: 287734
2016-11-23 10:07:04 +08:00
; RUN: llc -filetype=asm -o - -mtriple=armv7-apple-ios6.0.0 < %s | FileCheck %s
[XRay] ARM 32-bit no-Thumb support in LLVM This is a port of XRay to ARM 32-bit, without Thumb support yet. The XRay instrumentation support is moving up to AsmPrinter. This is one of 3 commits to different repositories of XRay ARM port. The other 2 are: https://reviews.llvm.org/D23932 (Clang test) https://reviews.llvm.org/D23933 (compiler-rt) Differential Revision: https://reviews.llvm.org/D23931 llvm-svn: 281878
2016-09-19 08:54:35 +08:00
define i32 @foo() nounwind noinline uwtable "function-instrument"="xray-always" {
; CHECK-LABEL: Lxray_sled_0:
; CHECK-NEXT: b #20
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-LABEL: Ltmp0:
ret i32 0
; CHECK-LABEL: Lxray_sled_1:
; CHECK-NEXT: b #20
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-LABEL: Ltmp1:
; CHECK-NEXT: bx lr
}
[XRay][CodeGen] Use PIC-friendly code in XRay sleds; remove synthetic references in .text Summary: This change achieves two things: - Redefine the Custom Event handling instrumentation points emitted by the compiler to not require dynamic relocation of references to the __xray_CustomEvent trampoline. - Remove the synthetic reference we emit at the end of a function that we used to keep auxiliary sections alive in favour of SHF_LINK_ORDER associated with the section where the function is defined. To achieve the custom event handling change, we've had to introduce the concept of sled versioning -- this will need to be supported by the runtime to allow us to understand how to turn on/off the new version of the custom event handling sleds. That change has to land first before we change the way we write the sleds. To remove the synthetic reference, we rely on a relatively new linker feature that preserves the sections that are associated with each other. This allows us to limit the effects on the .text section of ELF binaries. Because we're still using absolute references that are resolved at runtime for the instrumentation map (and function index) maps, we mark these sections write-able. In the future we can re-define the entries in the map to use relative relocations instead that can be statically determined by the linker. That change will be a bit more invasive so we defer this for later. Depends on D36816. Reviewers: dblaikie, echristo, pcc Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D36615 llvm-svn: 311525
2017-08-23 12:49:41 +08:00
; CHECK-LABEL: xray_instr_map
[XRay] Reduce synthetic references emitted by XRay Summary: When we're building with XRay instrumentation, we use a trick that preserves references from the function to a function sled index. This index table lives in a separate section, and without this trick the linker is free to garbage-collect this section and all the segments it refers to. Until we're able to tell the linkers to preserve these sections, we use this reference trick to keep around both the index and the entries in the instrumentation map. Before this change we emitted both a synthetic reference to the label in the instrumentation map, and to the entry in the function map index. This change removes the first synthetic reference and only emits one synthetic reference to the index -- the index entry has the references to the labels in the instrumentation map, so the linker will still preserve those if the function itself is preserved. This reduces the amount of synthetic references we emit from 16 bytes to just 8 bytes in x86_64, and similarly to other platforms. Reviewers: dblaikie Subscribers: javed.absar, kpw, pelikan, llvm-commits Differential Revision: https://reviews.llvm.org/D34340 llvm-svn: 305880
2017-06-21 14:39:42 +08:00
; CHECK-LABEL: Lxray_sleds_start0:
[XRay][Arm] Repair XRay table emission on Arm32 and add tests to identify such problem earlier Summary: Emission of XRay table was occasionally disabled for Arm32, but this bug was not then detected because earlier (also by mistake) testing of XRay was occasionally disabled on 32-bit Arm targets. This patch should fix that problem and detect such problems in the future. This patch is one of a series, see also - https://reviews.llvm.org/D28623 Reviewers: rengolin, dberris Reviewed By: dberris Subscribers: llvm-commits, aemerson, rengolin, dberris, iid_iunknown Differential Revision: https://reviews.llvm.org/D28624 llvm-svn: 292516
2017-01-20 04:24:23 +08:00
; CHECK: .long {{.*}}Lxray_sled_0
; CHECK: .long {{.*}}Lxray_sled_1
[XRay] Reduce synthetic references emitted by XRay Summary: When we're building with XRay instrumentation, we use a trick that preserves references from the function to a function sled index. This index table lives in a separate section, and without this trick the linker is free to garbage-collect this section and all the segments it refers to. Until we're able to tell the linkers to preserve these sections, we use this reference trick to keep around both the index and the entries in the instrumentation map. Before this change we emitted both a synthetic reference to the label in the instrumentation map, and to the entry in the function map index. This change removes the first synthetic reference and only emits one synthetic reference to the index -- the index entry has the references to the labels in the instrumentation map, so the linker will still preserve those if the function itself is preserved. This reduces the amount of synthetic references we emit from 16 bytes to just 8 bytes in x86_64, and similarly to other platforms. Reviewers: dblaikie Subscribers: javed.absar, kpw, pelikan, llvm-commits Differential Revision: https://reviews.llvm.org/D34340 llvm-svn: 305880
2017-06-21 14:39:42 +08:00
; CHECK-LABEL: Lxray_sleds_end0:
[XRay][CodeGen] Use PIC-friendly code in XRay sleds; remove synthetic references in .text Summary: This change achieves two things: - Redefine the Custom Event handling instrumentation points emitted by the compiler to not require dynamic relocation of references to the __xray_CustomEvent trampoline. - Remove the synthetic reference we emit at the end of a function that we used to keep auxiliary sections alive in favour of SHF_LINK_ORDER associated with the section where the function is defined. To achieve the custom event handling change, we've had to introduce the concept of sled versioning -- this will need to be supported by the runtime to allow us to understand how to turn on/off the new version of the custom event handling sleds. That change has to land first before we change the way we write the sleds. To remove the synthetic reference, we rely on a relatively new linker feature that preserves the sections that are associated with each other. This allows us to limit the effects on the .text section of ELF binaries. Because we're still using absolute references that are resolved at runtime for the instrumentation map (and function index) maps, we mark these sections write-able. In the future we can re-define the entries in the map to use relative relocations instead that can be statically determined by the linker. That change will be a bit more invasive so we defer this for later. Depends on D36816. Reviewers: dblaikie, echristo, pcc Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D36615 llvm-svn: 311525
2017-08-23 12:49:41 +08:00
; CHECK-LABEL: xray_fn_idx
[XRay] Reduce synthetic references emitted by XRay Summary: When we're building with XRay instrumentation, we use a trick that preserves references from the function to a function sled index. This index table lives in a separate section, and without this trick the linker is free to garbage-collect this section and all the segments it refers to. Until we're able to tell the linkers to preserve these sections, we use this reference trick to keep around both the index and the entries in the instrumentation map. Before this change we emitted both a synthetic reference to the label in the instrumentation map, and to the entry in the function map index. This change removes the first synthetic reference and only emits one synthetic reference to the index -- the index entry has the references to the labels in the instrumentation map, so the linker will still preserve those if the function itself is preserved. This reduces the amount of synthetic references we emit from 16 bytes to just 8 bytes in x86_64, and similarly to other platforms. Reviewers: dblaikie Subscribers: javed.absar, kpw, pelikan, llvm-commits Differential Revision: https://reviews.llvm.org/D34340 llvm-svn: 305880
2017-06-21 14:39:42 +08:00
; CHECK: .long {{.*}}xray_sleds_start0
; CHECK-NEXT: .long {{.*}}xray_sleds_end0
[XRay] Create an Index of sleds per function Summary: This change adds a new section to the xray-instrumented binary that stores an index into ranges of the instrumentation map, where sleds associated with the same function can be accessed as an array. At runtime, we can get access to this index by function ID offset allowing for selective patching and unpatching by function ID. Each entry in this new section (xray_fn_idx) will include two pointers indicating the start and one past the end of the sleds associated with the same function. These entries will be 16 bytes long on x86 and aarch64. On arm, we align to 16 bytes anyway so the runtime has to take that into consideration. __{start,stop}_xray_fn_idx will be the symbols that the runtime will look for when we implement the selective patching/unpatching by function id APIs. Because XRay synthesizes the function id's in a monotonically increasing manner at runtime now, implementations (and users) can use this table to look up the sleds associated with a specific function. This is useful in implementations that want to do things like: - Implement coverage mode for functions by patching everything pre-main, then as functions are encountered, the installed handler can unpatch the function that's been encountered after recording that it's been called. - Do "learning mode", so that the implementation can figure out some statistical information about function calls by function id for a time being, and then determine which functions are worth uninstrumenting at runtime. - Do "selective instrumentation" where an implementation can specifically instrument only certain function id's at runtime (either based on some external data, or through some other heuristics) instead of patching all the instrumented functions at runtime. Reviewers: dblaikie, echristo, chandlerc, javed.absar Subscribers: pelikan, aemerson, kpw, llvm-commits, rengolin Differential Revision: https://reviews.llvm.org/D32693 llvm-svn: 302109
2017-05-04 11:37:57 +08:00