[TailDuplicator] Fix copy instruction emitting into the wrong block.

The code for duplicating instructions could sometimes try to emit copies
intended to deal with unconstrainable register classes to the tail block of the
original instruction, rather than before the newly cloned instruction in the
predecessor block.

This was exposed by GlobalISel on arm64.

Differential Revision: https://reviews.llvm.org/D64049

llvm-svn: 364888

2 files changed, 126 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/TailDuplicator.cpp b/llvm/lib/CodeGen/TailDuplicator.cpp
index 4d3e02e3174..a0590a8a6cc 100644
--- a/llvm/lib/CodeGen/TailDuplicator.cpp
+++ b/llvm/lib/CodeGen/TailDuplicator.cpp
@@ -434,7 +434,7 @@ void TailDuplicator::duplicateInstruction(
             if (NewRC == nullptr)
               NewRC = OrigRC;
             unsigned NewReg = MRI->createVirtualRegister(NewRC);
-            BuildMI(*PredBB, MI, MI->getDebugLoc(),
+            BuildMI(*PredBB, NewMI, NewMI.getDebugLoc(),
                     TII->get(TargetOpcode::COPY), NewReg)
                 .addReg(VI->second.Reg, 0, VI->second.SubReg);
             LocalVRMap.erase(VI);
diff --git a/llvm/test/CodeGen/AArch64/taildup-inst-dup-loc.mir b/llvm/test/CodeGen/AArch64/taildup-inst-dup-loc.mir
new file mode 100644
index 00000000000..5954801d992
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/taildup-inst-dup-loc.mir
@@ -0,0 +1,125 @@
+# RUN: llc -mtriple aarch64 -run-pass=early-tailduplication -verify-machineinstrs %s -o - 2>&1 | FileCheck %s
+---
+name:            pluto
+tracksRegLiveness: true
+body:             |
+  ; This test checks that the COPY3 and COPY4 copies are correctly placed in the bb.5 block,
+  ; instead of crashing.
+
+  ; CHECK-LABEL: name: pluto
+  ; CHECK: bb.0:
+  ; CHECK:   successors: %bb.1(0x40000000), %bb.2(0x40000000)
+  ; CHECK:   liveins: $x0
+  ; CHECK:   [[DEF:%[0-9]+]]:gpr32 = IMPLICIT_DEF
+  ; CHECK:   [[DEF1:%[0-9]+]]:gpr32common = IMPLICIT_DEF
+  ; CHECK:   [[DEF2:%[0-9]+]]:gpr64 = IMPLICIT_DEF
+  ; CHECK:   [[DEF3:%[0-9]+]]:gpr64common = IMPLICIT_DEF
+  ; CHECK:   [[MOVi32imm:%[0-9]+]]:gpr32 = MOVi32imm 1
+  ; CHECK:   [[FMOVD0_:%[0-9]+]]:fpr64 = FMOVD0
+  ; CHECK:   TBNZW [[DEF]], 0, %bb.1
+  ; CHECK:   B %bb.2
+  ; CHECK: bb.1:
+  ; CHECK:   successors: %bb.9(0x80000000)
+  ; CHECK:   [[LDRXui:%[0-9]+]]:gpr64 = LDRXui [[DEF3]], 0 :: (load 8 from `i64* undef`)
+  ; CHECK:   B %bb.9
+  ; CHECK: bb.2:
+  ; CHECK:   successors: %bb.3(0x40000000), %bb.4(0x40000000)
+  ; CHECK:   $wzr = SUBSWri [[DEF1]], 19, 0, implicit-def $nzcv
+  ; CHECK:   [[CSINCWr:%[0-9]+]]:gpr32 = CSINCWr $wzr, $wzr, 1, implicit $nzcv
+  ; CHECK:   TBNZW [[CSINCWr]], 0, %bb.3
+  ; CHECK:   B %bb.4
+  ; CHECK: bb.3:
+  ; CHECK:   successors: %bb.9(0x80000000)
+  ; CHECK:   [[SCVTFUXDri:%[0-9]+]]:fpr64 = SCVTFUXDri [[DEF2]]
+  ; CHECK:   [[COPY:%[0-9]+]]:gpr64 = COPY [[SCVTFUXDri]]
+  ; CHECK:   [[COPY1:%[0-9]+]]:fpr64 = COPY [[SCVTFUXDri]]
+  ; CHECK:   B %bb.9
+  ; CHECK: bb.4:
+  ; CHECK:   successors: %bb.5(0x40000000), %bb.8(0x40000000)
+  ; CHECK:   TBNZW [[DEF]], 0, %bb.5
+  ; CHECK:   B %bb.8
+  ; CHECK: bb.5:
+  ; CHECK:   successors: %bb.9(0x80000000)
+  ; CHECK:   [[COPY2:%[0-9]+]]:fpr64 = COPY [[DEF2]]
+  ; CHECK:   [[COPY3:%[0-9]+]]:gpr64 = COPY [[COPY2]]
+  ; CHECK:   [[COPY4:%[0-9]+]]:fpr64 = COPY [[DEF2]]
+  ; CHECK:   B %bb.9
+  ; CHECK: bb.8:
+  ; CHECK:   successors: %bb.9(0x80000000)
+  ; CHECK: bb.9:
+  ; CHECK:   [[PHI:%[0-9]+]]:gpr64 = PHI [[LDRXui]], %bb.1, [[FMOVD0_]], %bb.8, [[COPY]], %bb.3, [[COPY3]], %bb.5
+  ; CHECK:   ADJCALLSTACKDOWN 0, 0, implicit-def $sp, implicit $sp
+  ; CHECK:   $d0 = COPY [[PHI]]
+  ; CHECK:   BL @pluto, csr_aarch64_aapcs, implicit-def $lr, implicit $sp, implicit $d0, implicit-def $d0
+  ; CHECK:   ADJCALLSTACKUP 0, 0, implicit-def $sp, implicit $sp
+  ; CHECK:   $w0 = COPY [[MOVi32imm]]
+  ; CHECK:   RET_ReallyLR implicit $w0
+
+  bb.1:
+    successors: %bb.2(0x40000000), %bb.3(0x40000000)
+    liveins: $x0
+
+    %1:gpr32 = IMPLICIT_DEF
+    %2:gpr32common = IMPLICIT_DEF
+    %5:gpr64 = IMPLICIT_DEF
+    %9:gpr64common = IMPLICIT_DEF
+    %13:gpr32 = MOVi32imm 1
+    %14:fpr64 = FMOVD0
+    TBNZW %1, 0, %bb.2
+    B %bb.3
+
+  bb.2:
+    successors: %bb.8(0x80000000)
+
+    %8:gpr64 = LDRXui %9, 0 :: (load 8 from `i64* undef`)
+    B %bb.8
+
+  bb.3:
+    successors: %bb.4(0x40000000), %bb.5(0x40000000)
+
+    $wzr = SUBSWri %2, 19, 0, implicit-def $nzcv
+    %15:gpr32 = CSINCWr $wzr, $wzr, 1, implicit $nzcv
+    TBNZW %15, 0, %bb.4
+    B %bb.5
+
+  bb.4:
+    successors: %bb.7(0x80000000)
+
+    %6:fpr64 = SCVTFUXDri %5
+    B %bb.7
+
+  bb.5:
+    successors: %bb.6(0x40000000), %bb.9(0x40000000)
+
+    TBNZW %1, 0, %bb.6
+    B %bb.9
+
+  bb.6:
+    successors: %bb.7(0x80000000)
+
+
+  bb.7:
+    successors: %bb.8(0x80000000)
+
+    %7:fpr64 = PHI %6, %bb.4, %5, %bb.6
+
+  bb.8:
+    successors: %bb.10(0x80000000)
+
+    %10:gpr64 = PHI %8, %bb.2, %7, %bb.7
+    B %bb.10
+
+  bb.9:
+    successors: %bb.10(0x80000000)
+
+
+  bb.10:
+    %11:gpr64 = PHI %10, %bb.8, %14, %bb.9
+    ADJCALLSTACKDOWN 0, 0, implicit-def $sp, implicit $sp
+    $d0 = COPY %11
+    BL @pluto, csr_aarch64_aapcs, implicit-def $lr, implicit $sp, implicit $d0, implicit-def $d0
+    ADJCALLSTACKUP 0, 0, implicit-def $sp, implicit $sp
+    $w0 = COPY %13
+    RET_ReallyLR implicit $w0
+
+...