[LV] Fix MinBWs in WidenIntrinsic case

[artagnon]

There is a bug in the computation and handling of MinBWs in the case of VPWidenIntrinsicRecipe: a crash is observed in VPlanTransforms::truncateToMinimalBitwidths due to a mismatch between the number of recipes processed and the number of entries in MinBWs. Fix handling of calls in llvm::computeMinimumValueSizes, and handle VPWidenIntrinsicRecipe in truncateToMinimalBitwidths, fixing the bug.

Fixes #87407.

[llvmbot]

@llvm/pr-subscribers-vectorizers
@llvm/pr-subscribers-llvm-analysis

@llvm/pr-subscribers-llvm-transforms

Author: Ramkumar Ramachandra (artagnon)

Changes

This bug is especially difficult to fix, since simplifyRecipes() simplifies the zext of 0 into the constant 0, removing an instruction and leaving a stale entry in the MinBWs map: a crash is subsequently observed in VPlanTransforms::truncateToMinimalBitwidths() due to a mismatch between the number of recipes processed and the number of entries in MinBWs. One possible way forward is to get simplifyRecipes() to erase entries from MinBWs when replacing Instructions with Constants.

Check in the test to ease investigation, while we plan a way to fix the bug.

---

Full diff: https://github.com/llvm/llvm-project/pull/137005.diff

1 Files Affected:

• (added) llvm/test/Transforms/LoopVectorize/pr87407.ll (+24)

diff --git a/llvm/test/Transforms/LoopVectorize/pr87407.ll b/llvm/test/Transforms/LoopVectorize/pr87407.ll
new file mode 100644
index 0000000000000..0983f2571e0b0
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/pr87407.ll
@@ -0,0 +1,24 @@
+; REQUIRES: asserts
+; RUN: not --crash opt -passes=loop-vectorize -disable-output %s
+
+define void @pr87407(ptr %dst, i64 %n) {
+entry:
+  %zext.0 = zext i8 0 to i64
+  br label %loop
+
+loop:
+  %iv = phi i64 [ %iv.next, %loop ], [ 0, %entry ]
+  %max = tail call i64 @llvm.umax.i64(i64 %zext.0, i64 0)
+  %cmp.max.0 = icmp ne i64 %max, 0
+  %zext.cmp = zext i1 %cmp.max.0 to i64
+  %trunc = trunc i64 %zext.cmp to i32
+  %shl = shl i32 %trunc, 8
+  %res = trunc i32 %shl to i8
+  %iv.next = add i64 %iv, 1
+  %exit.cond = icmp ne i64 %iv.next, %n
+  br i1 %exit.cond, label %loop, label %exit
+
+exit:
+  store i8 %res, ptr %dst, align 1
+  ret void
+}

[fhahn]

LGTM, thanks

[llvm-ci]

LLVM Buildbot has detected a new failure on builder lldb-aarch64-ubuntu running on linaro-lldb-aarch64-ubuntu while building llvm at step 6 "test".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/59/builds/16850

Here is the relevant piece of the build log for the reference

Step 6 (test) failure: build (failure)
...
PASS: lldb-api :: tools/lldb-server/TestGdbRemoteCompletion.py (1207 of 2151)
PASS: lldb-api :: tools/lldb-dap/attach/TestDAP_attach.py (1208 of 2151)
UNSUPPORTED: lldb-api :: tools/lldb-server/TestGdbRemoteFork.py (1209 of 2151)
UNSUPPORTED: lldb-api :: tools/lldb-server/TestGdbRemoteForkNonStop.py (1210 of 2151)
UNSUPPORTED: lldb-api :: tools/lldb-server/TestGdbRemoteForkResume.py (1211 of 2151)
PASS: lldb-api :: tools/lldb-server/TestGdbRemoteExitCode.py (1212 of 2151)
PASS: lldb-api :: tools/lldb-server/TestGdbRemoteHostInfo.py (1213 of 2151)
PASS: lldb-api :: tools/lldb-server/TestGdbRemoteModuleInfo.py (1214 of 2151)
PASS: lldb-api :: tools/lldb-server/TestGdbRemoteAuxvSupport.py (1215 of 2151)
UNRESOLVED: lldb-api :: tools/lldb-dap/variables/TestDAP_variables.py (1216 of 2151)
******************** TEST 'lldb-api :: tools/lldb-dap/variables/TestDAP_variables.py' FAILED ********************
Script:
--
/usr/bin/python3.10 /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/test/API/dotest.py -u CXXFLAGS -u CFLAGS --env LLVM_LIBS_DIR=/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./lib --env LLVM_INCLUDE_DIR=/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/include --env LLVM_TOOLS_DIR=/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin --arch aarch64 --build-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex --lldb-module-cache-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex/module-cache-lldb/lldb-api --clang-module-cache-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex/module-cache-clang/lldb-api --executable /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin/lldb --compiler /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin/clang --dsymutil /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin/dsymutil --make /usr/bin/gmake --llvm-tools-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./bin --lldb-obj-root /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/tools/lldb --lldb-libs-dir /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/./lib /home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/llvm-project/lldb/test/API/tools/lldb-dap/variables -p TestDAP_variables.py
--
Exit Code: 1

Command Output (stdout):
--
lldb version 21.0.0git (https://github.com/llvm/llvm-project.git revision 49842426f3fc70af756f9e6fe80ecf829178a1b2)
  clang revision 49842426f3fc70af756f9e6fe80ecf829178a1b2
  llvm revision 49842426f3fc70af756f9e6fe80ecf829178a1b2
Skipping the following test categories: ['libc++', 'dsym', 'gmodules', 'debugserver', 'objc']

--
Command Output (stderr):
--
UNSUPPORTED: LLDB (/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/bin/clang-aarch64) :: test_darwin_dwarf_missing_obj (TestDAP_variables.TestDAP_variables) (requires one of macosx, darwin, ios, tvos, watchos, bridgeos, iphonesimulator, watchsimulator, appletvsimulator) 
UNSUPPORTED: LLDB (/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/bin/clang-aarch64) :: test_darwin_dwarf_missing_obj_with_symbol_ondemand_enabled (TestDAP_variables.TestDAP_variables) (requires one of macosx, darwin, ios, tvos, watchos, bridgeos, iphonesimulator, watchsimulator, appletvsimulator) 
========= DEBUG ADAPTER PROTOCOL LOGS =========
1745916978.636748075 --> (stdin/stdout) {"command":"initialize","type":"request","arguments":{"adapterID":"lldb-native","clientID":"vscode","columnsStartAt1":true,"linesStartAt1":true,"locale":"en-us","pathFormat":"path","supportsRunInTerminalRequest":true,"supportsVariablePaging":true,"supportsVariableType":true,"supportsStartDebuggingRequest":true,"supportsProgressReporting":true,"$__lldb_sourceInitFile":false},"seq":1}
1745916978.638991356 <-- (stdin/stdout) {"body":{"$__lldb_version":"lldb version 21.0.0git (https://github.com/llvm/llvm-project.git revision 49842426f3fc70af756f9e6fe80ecf829178a1b2)\n  clang revision 49842426f3fc70af756f9e6fe80ecf829178a1b2\n  llvm revision 49842426f3fc70af756f9e6fe80ecf829178a1b2","completionTriggerCharacters":["."," ","\t"],"exceptionBreakpointFilters":[{"default":false,"filter":"cpp_catch","label":"C++ Catch"},{"default":false,"filter":"cpp_throw","label":"C++ Throw"},{"default":false,"filter":"objc_catch","label":"Objective-C Catch"},{"default":false,"filter":"objc_throw","label":"Objective-C Throw"}],"supportTerminateDebuggee":true,"supportsBreakpointLocationsRequest":true,"supportsCancelRequest":true,"supportsCompletionsRequest":true,"supportsConditionalBreakpoints":true,"supportsConfigurationDoneRequest":true,"supportsDataBreakpoints":true,"supportsDelayedStackTraceLoading":true,"supportsDisassembleRequest":true,"supportsEvaluateForHovers":true,"supportsExceptionInfoRequest":true,"supportsExceptionOptions":true,"supportsFunctionBreakpoints":true,"supportsHitConditionalBreakpoints":true,"supportsInstructionBreakpoints":true,"supportsLogPoints":true,"supportsModulesRequest":true,"supportsReadMemoryRequest":true,"supportsRestartRequest":true,"supportsSetVariable":true,"supportsStepInTargetsRequest":true,"supportsSteppingGranularity":true,"supportsValueFormattingOptions":true},"command":"initialize","request_seq":1,"seq":0,"success":true,"type":"response"}
1745916978.639234543 --> (stdin/stdout) {"command":"launch","type":"request","arguments":{"program":"/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex/tools/lldb-dap/variables/TestDAP_variables.test_indexedVariables/a.out","initCommands":["settings clear -all","settings set symbols.enable-external-lookup false","settings set target.inherit-tcc true","settings set target.disable-aslr false","settings set target.detach-on-error false","settings set target.auto-apply-fixits false","settings set plugin.process.gdb-remote.packet-timeout 60","settings set symbols.clang-modules-cache-path \"/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex/module-cache-lldb/lldb-api\"","settings set use-color false","settings set show-statusline false"],"disableASLR":false,"enableAutoVariableSummaries":false,"enableSyntheticChildDebugging":false,"displayExtendedBacktrace":false},"seq":2}
1745916978.639461994 <-- (stdin/stdout) {"body":{"category":"console","output":"Running initCommands:\n"},"event":"output","seq":0,"type":"event"}
1745916978.639491558 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings clear -all\n"},"event":"output","seq":0,"type":"event"}
1745916978.639502287 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings set symbols.enable-external-lookup false\n"},"event":"output","seq":0,"type":"event"}
1745916978.639511347 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings set target.inherit-tcc true\n"},"event":"output","seq":0,"type":"event"}
1745916978.639519215 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings set target.disable-aslr false\n"},"event":"output","seq":0,"type":"event"}
1745916978.639527082 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings set target.detach-on-error false\n"},"event":"output","seq":0,"type":"event"}
1745916978.639535189 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings set target.auto-apply-fixits false\n"},"event":"output","seq":0,"type":"event"}
1745916978.639542818 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings set plugin.process.gdb-remote.packet-timeout 60\n"},"event":"output","seq":0,"type":"event"}
1745916978.639565229 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings set symbols.clang-modules-cache-path \"/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex/module-cache-lldb/lldb-api\"\n"},"event":"output","seq":0,"type":"event"}
1745916978.639576435 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings set use-color false\n"},"event":"output","seq":0,"type":"event"}
1745916978.639584303 <-- (stdin/stdout) {"body":{"category":"console","output":"(lldb) settings set show-statusline false\n"},"event":"output","seq":0,"type":"event"}
1745916978.716892242 <-- (stdin/stdout) {"command":"launch","request_seq":2,"seq":0,"success":true,"type":"response"}
1745916978.716927290 <-- (stdin/stdout) {"body":{"module":{"addressRange":"281473111613440","id":"46771E9A-54FF-F825-3560-60BC1C8B4A44-C1108BF8","name":"ld-linux-aarch64.so.1","path":"/usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1","symbolStatus":"Symbols not found."},"reason":"new"},"event":"module","seq":0,"type":"event"}
1745916978.716952562 <-- (stdin/stdout) {"body":{"isLocalProcess":true,"name":"/home/tcwg-buildbot/worker/lldb-aarch64-ubuntu/build/lldb-test-build.noindex/tools/lldb-dap/variables/TestDAP_variables.test_indexedVariables/a.out","startMethod":"launch","systemProcessId":2831874},"event":"process","seq":0,"type":"event"}
1745916978.716962814 <-- (stdin/stdout) {"event":"initialized","seq":0,"type":"event"}
1745916978.716968536 <-- (stdin/stdout) {"body":{"module":{"addressRange":"281473111846912","id":"4A8F74F7-08C0-3C8C-B911-12040A09904C-51F3DA5C","name":"[vdso]","path":"[vdso]","symbolStatus":"Symbols not found."},"reason":"new"},"event":"module","seq":0,"type":"event"}