[GlobalISel] Adding support for handling G_ASSERT_{SEXT,ZEXT,ALIGN} i… (#74196)

…n artifact combiner

These instructions are hint for optimizations and can be treated as
copies and are handled as such with this change. Without it is possible
to run into an assertion, since tryCombineUnmergeValues rightfully use
getDefIgnoringCopies to get the source MI, which already handle these
hint instructions and treat them as copies. The problem is that
markDefDead only considers COPYs, which will lead to crash with
assertion for cases like testUnmergeHintOfTrunc.

Author: dfszabo

llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h

@@ -1366,6 +1366,9 @@ class LegalizationArtifactCombiner {
           // Adding Use to ArtifactList.
           WrapperObserver.changedInstr(Use);
           break;
+        case TargetOpcode::G_ASSERT_SEXT:
+        case TargetOpcode::G_ASSERT_ZEXT:
+        case TargetOpcode::G_ASSERT_ALIGN:
         case TargetOpcode::COPY: {
           Register Copy = Use.getOperand(0).getReg();
           if (Copy.isVirtual())
@@ -1392,6 +1395,9 @@ class LegalizationArtifactCombiner {
     case TargetOpcode::G_ANYEXT:
     case TargetOpcode::G_SEXT:
     case TargetOpcode::G_EXTRACT:
+    case TargetOpcode::G_ASSERT_SEXT:
+    case TargetOpcode::G_ASSERT_ZEXT:
+    case TargetOpcode::G_ASSERT_ALIGN:
       return MI.getOperand(1).getReg();
     case TargetOpcode::G_UNMERGE_VALUES:
       return MI.getOperand(MI.getNumOperands() - 1).getReg();
@@ -1425,7 +1431,8 @@ class LegalizationArtifactCombiner {
       if (MRI.hasOneUse(PrevRegSrc)) {
         if (TmpDef != &DefMI) {
           assert((TmpDef->getOpcode() == TargetOpcode::COPY ||
-                  isArtifactCast(TmpDef->getOpcode())) &&
+                  isArtifactCast(TmpDef->getOpcode()) ||
+                  isPreISelGenericOptimizationHint(TmpDef->getOpcode())) &&
                  "Expecting copy or artifact cast here");
 
           DeadInsts.push_back(TmpDef);
@@ -1509,16 +1516,8 @@ class LegalizationArtifactCombiner {
   /// Looks through copy instructions and returns the actual
   /// source register.
   Register lookThroughCopyInstrs(Register Reg) {
-    using namespace llvm::MIPatternMatch;
-
-    Register TmpReg;
-    while (mi_match(Reg, MRI, m_Copy(m_Reg(TmpReg)))) {
-      if (MRI.getType(TmpReg).isValid())
-        Reg = TmpReg;
-      else
-        break;
-    }
-    return Reg;
+    Register TmpReg = getSrcRegIgnoringCopies(Reg, MRI);
+    return TmpReg.isValid() ? TmpReg : Reg;
   }
 };
 

llvm/test/CodeGen/AArch64/GlobalISel/irtranslator-hoisted-constants.ll

@@ -46,14 +46,11 @@ define i32 @test(i32 %a, i1 %c) {
   ; PRESELECTION-NEXT: {{  $}}
   ; PRESELECTION-NEXT:   [[COPY:%[0-9]+]]:gpr(s32) = COPY $w0
   ; PRESELECTION-NEXT:   [[COPY1:%[0-9]+]]:gpr(s32) = COPY $w1
-  ; PRESELECTION-NEXT:   [[TRUNC:%[0-9]+]]:gpr(s8) = G_TRUNC [[COPY1]](s32)
-  ; PRESELECTION-NEXT:   [[ASSERT_ZEXT:%[0-9]+]]:gpr(s8) = G_ASSERT_ZEXT [[TRUNC]], 1
   ; PRESELECTION-NEXT:   [[C:%[0-9]+]]:gpr(s32) = G_CONSTANT i32 0
   ; PRESELECTION-NEXT:   [[C1:%[0-9]+]]:gpr(s32) = G_CONSTANT i32 100000
   ; PRESELECTION-NEXT:   [[CONSTANT_FOLD_BARRIER:%[0-9]+]]:gpr(s32) = G_CONSTANT_FOLD_BARRIER [[C1]]
-  ; PRESELECTION-NEXT:   [[ANYEXT:%[0-9]+]]:gpr(s32) = G_ANYEXT [[ASSERT_ZEXT]](s8)
   ; PRESELECTION-NEXT:   [[C2:%[0-9]+]]:gpr(s32) = G_CONSTANT i32 1
-  ; PRESELECTION-NEXT:   [[AND:%[0-9]+]]:gpr(s32) = G_AND [[ANYEXT]], [[C2]]
+  ; PRESELECTION-NEXT:   [[AND:%[0-9]+]]:gpr(s32) = G_AND [[COPY1]], [[C2]]
   ; PRESELECTION-NEXT:   G_BRCOND [[AND]](s32), %bb.3
   ; PRESELECTION-NEXT:   G_BR %bb.2
   ; PRESELECTION-NEXT: {{  $}}

llvm/test/CodeGen/AArch64/GlobalISel/legalize-simple.mir

@@ -136,6 +136,47 @@ body:             |
     $x0 = COPY %3(s64)
     RET_ReallyLR implicit $x0
 
+...
+---
+name:            testExtOfHintOfTrunc
+body:             |
+  bb.0:
+    liveins: $x0
+
+    ; CHECK-LABEL: name: testExtOfHintOfTrunc
+    ; CHECK: liveins: $x0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+    ; CHECK-NEXT: $x0 = COPY [[COPY]](s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %0:_(s64) = COPY $x0
+    %1:_(s8) = G_TRUNC %0(s64)
+    %2:_(s8) = G_ASSERT_ZEXT %1(s8), 1
+    %3:_(s64) = G_ANYEXT %2(s8)
+    $x0 = COPY %3(s64)
+    RET_ReallyLR implicit $x0
+
+...
+---
+name:            testExtOfCopyAndHintOfTrunc
+body:             |
+  bb.0:
+    liveins: $x0
+
+    ; CHECK-LABEL: name: testExtOfCopyAndHintOfTrunc
+    ; CHECK: liveins: $x0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+    ; CHECK-NEXT: $x0 = COPY [[COPY]](s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %0:_(s64) = COPY $x0
+    %1:_(s8) = G_TRUNC %0(s64)
+    %2:_(s8) = COPY %1(s8)
+    %3:_(s8) = G_ASSERT_ZEXT %2(s8), 1
+    %4:_(s64) = G_ANYEXT %3(s8)
+    $x0 = COPY %4(s64)
+    RET_ReallyLR implicit $x0
+
 ...
 ---
 name:            testExtOf2CopyOfTrunc
@@ -158,3 +199,26 @@ body:             |
     RET_ReallyLR implicit $x0
 
 ...
+---
+name:            testUnmergeHintOfTrunc
+body:             |
+  bb.0:
+    liveins: $x0
+
+    ; CHECK-LABEL: name: testUnmergeHintOfTrunc
+    ; CHECK: liveins: $x0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
+    ; CHECK-NEXT: [[UV:%[0-9]+]]:_(s8), [[UV1:%[0-9]+]]:_(s8), [[UV2:%[0-9]+]]:_(s8), [[UV3:%[0-9]+]]:_(s8), [[UV4:%[0-9]+]]:_(s8), [[UV5:%[0-9]+]]:_(s8), [[UV6:%[0-9]+]]:_(s8), [[UV7:%[0-9]+]]:_(s8) = G_UNMERGE_VALUES [[COPY]](s64)
+    ; CHECK-NEXT: [[ANYEXT:%[0-9]+]]:_(s64) = G_ANYEXT [[UV1]](s8)
+    ; CHECK-NEXT: $x0 = COPY [[ANYEXT]](s64)
+    ; CHECK-NEXT: RET_ReallyLR implicit $x0
+    %0:_(s64) = COPY $x0
+    %1:_(s16) = G_TRUNC %0(s64)
+    %2:_(s16) = G_ASSERT_ZEXT %1(s16), 1
+    %3:_(s8), %4:_(s8) = G_UNMERGE_VALUES %2(s16)
+    %5:_(s64) = G_ANYEXT %4(s8)
+    $x0 = COPY %5(s64)
+    RET_ReallyLR implicit $x0
+
+...