[RISCV] Clear kill flags after replaceRegWith in RISCVFoldMemOffset.

[topperc]

Any kill flags that were present for the old register are not valid for the replacement and the replacement may have extended the live range of the replacement register.

[llvmbot]

@llvm/pr-subscribers-backend-risc-v

Author: Craig Topper (topperc)

Changes

Any kill flags that were present for the old register are not valid for the replacement and the replacement may have extended the live range of the replacement register.

---

Full diff: https://github.com/llvm/llvm-project/pull/136762.diff

2 Files Affected:

• (modified) llvm/lib/Target/RISCV/RISCVFoldMemOffset.cpp (+1)
• (added) llvm/test/CodeGen/RISCV/fold-mem-offset.mir (+43)

diff --git a/llvm/lib/Target/RISCV/RISCVFoldMemOffset.cpp b/llvm/lib/Target/RISCV/RISCVFoldMemOffset.cpp
index 989e9d859d64f..aa8da1486faca 100644
--- a/llvm/lib/Target/RISCV/RISCVFoldMemOffset.cpp
+++ b/llvm/lib/Target/RISCV/RISCVFoldMemOffset.cpp
@@ -274,6 +274,7 @@ bool RISCVFoldMemOffset::runOnMachineFunction(MachineFunction &MF) {
         MemMI->getOperand(2).setImm(NewOffset);
 
       MRI.replaceRegWith(MI.getOperand(0).getReg(), MI.getOperand(1).getReg());
+      MRI.clearKillFlags(MI.getOperand(1).getReg());
       MI.eraseFromParent();
     }
   }
diff --git a/llvm/test/CodeGen/RISCV/fold-mem-offset.mir b/llvm/test/CodeGen/RISCV/fold-mem-offset.mir
new file mode 100644
index 0000000000000..17cec6e6f8b9c
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/fold-mem-offset.mir
@@ -0,0 +1,43 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+# RUN: llc %s -mtriple=riscv32 -run-pass=riscv-fold-mem-offset -verify-machineinstrs | FileCheck %s
+
+---
+name:            crash
+tracksRegLiveness: true
+noPhis:          false
+isSSA:           true
+noVRegs:         false
+hasFakeUses:     false
+body:             |
+  bb.0:
+    liveins: $x10, $x11
+
+    ; CHECK-LABEL: name: crash
+    ; CHECK: liveins: $x10, $x11
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:gpr = COPY $x11
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:gpr = COPY $x10
+    ; CHECK-NEXT: [[SLLI:%[0-9]+]]:gpr = SLLI [[COPY]], 3
+    ; CHECK-NEXT: [[ADD:%[0-9]+]]:gpr = ADD killed [[SLLI]], [[COPY1]]
+    ; CHECK-NEXT: [[LUI:%[0-9]+]]:gpr = LUI 23
+    ; CHECK-NEXT: [[ADD1:%[0-9]+]]:gpr = ADD [[ADD]], [[LUI]]
+    ; CHECK-NEXT: [[ADD2:%[0-9]+]]:gpr = ADD [[ADD]], [[LUI]]
+    ; CHECK-NEXT: [[LW:%[0-9]+]]:gpr = LW killed [[ADD2]], 1792
+    ; CHECK-NEXT: [[LW1:%[0-9]+]]:gpr = LW killed [[ADD1]], 1796
+    ; CHECK-NEXT: $x10 = COPY [[LW]]
+    ; CHECK-NEXT: $x11 = COPY [[LW1]]
+    ; CHECK-NEXT: PseudoRET implicit $x10, implicit $x11
+    %1:gpr = COPY $x11
+    %0:gpr = COPY $x10
+    %3:gpr = SLLI %1, 3
+    %4:gpr = ADD killed %3, %0
+    %5:gpr = LUI 23
+    %6:gpr = ADDI %5, 1792
+    %7:gpr = ADD %4, killed %6
+    %8:gpr = ADD %4, %5
+    %9:gpr = LW killed %8, 1792
+    %10:gpr = LW killed %7, 4
+    $x10 = COPY %9
+    $x11 = COPY %10
+    PseudoRET implicit $x10, implicit $x11
+...

[preames]

LGTM

[llvm-ci]

LLVM Buildbot has detected a new failure on builder llvm-clang-x86_64-gcc-ubuntu-no-asserts running on doug-worker-6 while building llvm at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/202/builds/836

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

Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'AddressSanitizer-x86_64-linux-dynamic :: TestCases/asan_lsan_deadlock.cpp' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
/home/buildbot/buildbot-root/gcc-no-asserts/build/./bin/clang  --driver-mode=g++ -fsanitize=address -mno-omit-leaf-frame-pointer -fno-omit-frame-pointer -fno-optimize-sibling-calls -gline-tables-only  -m64  -shared-libasan -O0 /home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/compiler-rt/test/asan/TestCases/asan_lsan_deadlock.cpp -o /home/buildbot/buildbot-root/gcc-no-asserts/build/runtimes/runtimes-bins/compiler-rt/test/asan/X86_64LinuxDynamicConfig/TestCases/Output/asan_lsan_deadlock.cpp.tmp # RUN: at line 4
+ /home/buildbot/buildbot-root/gcc-no-asserts/build/./bin/clang --driver-mode=g++ -fsanitize=address -mno-omit-leaf-frame-pointer -fno-omit-frame-pointer -fno-optimize-sibling-calls -gline-tables-only -m64 -shared-libasan -O0 /home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/compiler-rt/test/asan/TestCases/asan_lsan_deadlock.cpp -o /home/buildbot/buildbot-root/gcc-no-asserts/build/runtimes/runtimes-bins/compiler-rt/test/asan/X86_64LinuxDynamicConfig/TestCases/Output/asan_lsan_deadlock.cpp.tmp
env ASAN_OPTIONS=detect_leaks=1 not  /home/buildbot/buildbot-root/gcc-no-asserts/build/runtimes/runtimes-bins/compiler-rt/test/asan/X86_64LinuxDynamicConfig/TestCases/Output/asan_lsan_deadlock.cpp.tmp 2>&1 | FileCheck /home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/compiler-rt/test/asan/TestCases/asan_lsan_deadlock.cpp # RUN: at line 5
+ env ASAN_OPTIONS=detect_leaks=1 not /home/buildbot/buildbot-root/gcc-no-asserts/build/runtimes/runtimes-bins/compiler-rt/test/asan/X86_64LinuxDynamicConfig/TestCases/Output/asan_lsan_deadlock.cpp.tmp
+ FileCheck /home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/compiler-rt/test/asan/TestCases/asan_lsan_deadlock.cpp
�[1m/home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/compiler-rt/test/asan/TestCases/asan_lsan_deadlock.cpp:61:12: �[0m�[0;1;31merror: �[0m�[1mCHECK: expected string not found in input
�[0m // CHECK: SUMMARY: AddressSanitizer: stack-buffer-overflow
�[0;1;32m           ^
�[0m�[1m<stdin>:1:1: �[0m�[0;1;30mnote: �[0m�[1mscanning from here
�[0m=================================================================
�[0;1;32m^
�[0m�[1m<stdin>:2:10: �[0m�[0;1;30mnote: �[0m�[1mpossible intended match here
�[0m==2333968==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x75581d309034 at pc 0x61a174325280 bp 0x75581b1ffce0 sp 0x75581b1ffcd8
�[0;1;32m         ^
�[0m
Input file: <stdin>
Check file: /home/buildbot/buildbot-root/gcc-no-asserts/llvm-project/compiler-rt/test/asan/TestCases/asan_lsan_deadlock.cpp

-dump-input=help explains the following input dump.

Input was:
<<<<<<
�[1m�[0m�[0;1;30m            1: �[0m�[1m�[0;1;46m================================================================= �[0m
�[0;1;31mcheck:61'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
�[0m�[0;1;30m            2: �[0m�[1m�[0;1;46m==2333968==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x75581d309034 at pc 0x61a174325280 bp 0x75581b1ffce0 sp 0x75581b1ffcd8 �[0m
�[0;1;31mcheck:61'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
�[0m�[0;1;35mcheck:61'1              ?                                                                                                                                    possible intended match
�[0m�[0;1;30m            3: �[0m�[1m�[0;1;46mWRITE of size 4 at 0x75581d309034 thread T2 �[0m
�[0;1;31mcheck:61'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
�[0m�[0;1;30m            4: �[0m�[1m�[0;1;46mTimeout! Deadlock detected. �[0m
�[0;1;31mcheck:61'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
�[0m>>>>>>

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