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llvm-project/llvm/test/CodeGen/X86/critical-anti-dep-breaker.ll

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critical-anti-dependency breaker: don't use reg def info from kill insts (PR20308) In PR20308 ( http://llvm.org/bugs/show_bug.cgi?id=20308 ), the critical-anti-dependency breaker caused a miscompile because it broke a WAR hazard using a register that it thinks is available based on info from a kill inst. Until PR18663 is solved, we shouldn't use any def/use info from a kill because they are really just nops. This patch adds guard checks for kills around calls to ScanInstruction() where the DefIndices array is set. For good measure, add an assert in ScanInstruction() so we don't hit this bug again. The test case is a reduced version of the code from the bug report. Differential Revision: http://reviews.llvm.org/D4977 llvm-svn: 216114
2014-08-21 02:03:00 +08:00
; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -relocation-model=pic -post-RA-scheduler=1 -break-anti-dependencies=critical | FileCheck %s
; PR20308 ( http://llvm.org/bugs/show_bug.cgi?id=20308 )
; The critical-anti-dependency-breaker must not use register def information from a kill inst.
; This test case expects such an instruction to appear as a comment with def info for RDI.
; There is an anti-dependency (WAR) hazard using RAX using default reg allocation and scheduling.
; The post-RA-scheduler and critical-anti-dependency breaker can eliminate that hazard using R10.
; That is the first free register that isn't used as a param in the call to "@Image".
@PartClass = external global i32
@NullToken = external global i64
; CHECK-LABEL: Part_Create:
MachineCopyPropagation: Remove the copies instead of using KILL instructions. For some history here see the commit messages of r199797 and r169060. The original intent was to fix cases like: %EAX<def> = COPY %ECX<kill>, %RAX<imp-def> %RCX<def> = COPY %RAX<kill> where simply removing the copies would have RCX undefined as in terms of machine operands only the ECX part of it is defined. The machine verifier would complain about this so 169060 changed such COPY instructions into KILL instructions so some super-register imp-defs would be preserved. In r199797 it was finally decided to always do this regardless of super-register defs. But this is wrong, consider: R1 = COPY R0 ... R0 = COPY R1 getting changed to: R1 = KILL R0 ... R0 = KILL R1 It now looks like R0 dies at the first KILL and won't be alive until the second KILL, while in reality R0 is alive and must not change in this part of the program. As this only happens after register allocation there is not much code still performing liveness queries so the issue was not noticed. In fact I didn't manage to create a testcase for this, without unrelated changes I am working on at the moment. The fix is simple: As of r223896 the MachineVerifier allows reads from partially defined registers, so the whole transforming COPY->KILL thing is not necessary anymore. This patch also changes a similar (but more benign case as the def and src are the same register) case in the VirtRegRewriter. Differential Revision: http://reviews.llvm.org/D10117 llvm-svn: 238588
2015-05-30 02:19:25 +08:00
; CHECK: movq PartClass@GOTPCREL(%rip), %r10
critical-anti-dependency breaker: don't use reg def info from kill insts (PR20308) In PR20308 ( http://llvm.org/bugs/show_bug.cgi?id=20308 ), the critical-anti-dependency breaker caused a miscompile because it broke a WAR hazard using a register that it thinks is available based on info from a kill inst. Until PR18663 is solved, we shouldn't use any def/use info from a kill because they are really just nops. This patch adds guard checks for kills around calls to ScanInstruction() where the DefIndices array is set. For good measure, add an assert in ScanInstruction() so we don't hit this bug again. The test case is a reduced version of the code from the bug report. Differential Revision: http://reviews.llvm.org/D4977 llvm-svn: 216114
2014-08-21 02:03:00 +08:00
define i32 @Part_Create(i64* %Anchor, i32 %TypeNum, i32 %F, i32 %Z, i32* %Status, i64* %PartTkn) {
%PartObj = alloca i64*, align 8
%Vchunk = alloca i64, align 8
[opaque pointer type] Add textual IR support for explicit type parameter to load instruction Essentially the same as the GEP change in r230786. A similar migration script can be used to update test cases, though a few more test case improvements/changes were required this time around: (r229269-r229278) import fileinput import sys import re pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)") for line in sys.stdin: sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line)) Reviewers: rafael, dexonsmith, grosser Differential Revision: http://reviews.llvm.org/D7649 llvm-svn: 230794
2015-02-28 05:17:42 +08:00
%1 = load i64, i64* @NullToken, align 4
critical-anti-dependency breaker: don't use reg def info from kill insts (PR20308) In PR20308 ( http://llvm.org/bugs/show_bug.cgi?id=20308 ), the critical-anti-dependency breaker caused a miscompile because it broke a WAR hazard using a register that it thinks is available based on info from a kill inst. Until PR18663 is solved, we shouldn't use any def/use info from a kill because they are really just nops. This patch adds guard checks for kills around calls to ScanInstruction() where the DefIndices array is set. For good measure, add an assert in ScanInstruction() so we don't hit this bug again. The test case is a reduced version of the code from the bug report. Differential Revision: http://reviews.llvm.org/D4977 llvm-svn: 216114
2014-08-21 02:03:00 +08:00
store i64 %1, i64* %Vchunk, align 8
[opaque pointer type] Add textual IR support for explicit type parameter to load instruction Essentially the same as the GEP change in r230786. A similar migration script can be used to update test cases, though a few more test case improvements/changes were required this time around: (r229269-r229278) import fileinput import sys import re pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)") for line in sys.stdin: sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line)) Reviewers: rafael, dexonsmith, grosser Differential Revision: http://reviews.llvm.org/D7649 llvm-svn: 230794
2015-02-28 05:17:42 +08:00
%2 = load i32, i32* @PartClass, align 4
critical-anti-dependency breaker: don't use reg def info from kill insts (PR20308) In PR20308 ( http://llvm.org/bugs/show_bug.cgi?id=20308 ), the critical-anti-dependency breaker caused a miscompile because it broke a WAR hazard using a register that it thinks is available based on info from a kill inst. Until PR18663 is solved, we shouldn't use any def/use info from a kill because they are really just nops. This patch adds guard checks for kills around calls to ScanInstruction() where the DefIndices array is set. For good measure, add an assert in ScanInstruction() so we don't hit this bug again. The test case is a reduced version of the code from the bug report. Differential Revision: http://reviews.llvm.org/D4977 llvm-svn: 216114
2014-08-21 02:03:00 +08:00
call i32 @Image(i64* %Anchor, i32 %2, i32 0, i32 0, i32* %Status, i64* %PartTkn, i64** %PartObj)
call i32 @Create(i64* %Anchor)
ret i32 %2
}
declare i32 @Image(i64*, i32, i32, i32, i32*, i64*, i64**)
declare i32 @Create(i64*)