[InstCombine] Add users of phi when nsw/nuw flags of add are inferred

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp

@@ -1868,6 +1868,13 @@ Instruction *InstCombinerImpl::visitAdd(BinaryOperator &I) {
   if (Instruction *Res = foldBinOpOfSelectAndCastOfSelectCondition(I))
     return Res;
 
+  if (Changed) {
+    for (User *U : I.users()) {
+      if (auto *PHI = dyn_cast<PHINode>(U))
+        Worklist.pushUsersToWorkList(*PHI);
+    }
+  }
+
   return Changed ? &I : nullptr;
 }
 

llvm/test/Transforms/InstCombine/2007-10-31-RangeCrash.ll

@@ -1,25 +1,18 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
 ; RUN: opt < %s -S -passes=instcombine | FileCheck %s
 
-; We do not reach a fixpoint, because we first have to infer nsw on the IV add,
-; and could eliminate the icmp slt afterwards, but don't revisit it.
-
 target datalayout = "E-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f128:64:128"
 
-define i32 @test() "instcombine-no-verify-fixpoint" {
-; CHECK-LABEL: define i32 @test(
-; CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
+define i32 @test() {
+; CHECK-LABEL: define i32 @test() {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br i1 true, label [[BB_I:%.*]], label [[CALCULATECOLORSPECIFICBLACKLEVEL_EXIT:%.*]]
 ; CHECK:       bb.i:
 ; CHECK-NEXT:    br label [[BB51_I_I:%.*]]
 ; CHECK:       bb27.i.i:
-; CHECK-NEXT:    [[TMP50_I_I:%.*]] = add nsw i32 [[X_0_I_I:%.*]], 2
 ; CHECK-NEXT:    br label [[BB51_I_I]]
 ; CHECK:       bb51.i.i:
-; CHECK-NEXT:    [[X_0_I_I]] = phi i32 [ [[TMP50_I_I]], [[BB27_I_I:%.*]] ], [ 0, [[BB_I]] ]
-; CHECK-NEXT:    [[TMP54_I_I:%.*]] = icmp slt i32 [[X_0_I_I]], 0
-; CHECK-NEXT:    br i1 [[TMP54_I_I]], label [[BB27_I_I]], label [[BB57_I_I:%.*]]
+; CHECK-NEXT:    br i1 false, label [[BB27_I_I:%.*]], label [[BB57_I_I:%.*]]
 ; CHECK:       bb57.i.i:
 ; CHECK-NEXT:    ret i32 0
 ; CHECK:       calculateColorSpecificBlackLevel.exit:

llvm/test/Transforms/InstCombine/cast_phi.ll

@@ -316,7 +316,7 @@ define i8 @trunc_in_loop_exit_block() "instcombine-no-verify-fixpoint" {
 ; CHECK:       loop:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP_LATCH:%.*]] ]
 ; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ 1, [[ENTRY]] ], [ [[IV_NEXT]], [[LOOP_LATCH]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[IV]], 100
+; CHECK-NEXT:    [[CMP:%.*]] = icmp samesign ult i32 [[IV]], 100
 ; CHECK-NEXT:    br i1 [[CMP]], label [[LOOP_LATCH]], label [[EXIT:%.*]]
 ; CHECK:       loop.latch:
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i32 [[IV]], 1

llvm/test/Transforms/SimpleLoopUnswitch/2007-08-01-LCSSA.ll

@@ -1,40 +1,29 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
 ; RUN: opt < %s -S -passes='loop(simple-loop-unswitch),instcombine' -verify-memoryssa | FileCheck %s
 
-; We do not reach a fixpoint, because we first have to infer nsw on the IV add,
-; and could eliminate the icmp slt afterwards, but don't revisit it.
-
 @.str9 = external constant [1 x i8]
 
 declare i32 @strcmp(ptr, ptr)
 
-define i32 @_ZN9Generator6strregEPKc(ptr %this, ptr %s) "instcombine-no-verify-fixpoint" {
+define i32 @_ZN9Generator6strregEPKc(ptr %this, ptr %s) {
 ; CHECK-LABEL: define i32 @_ZN9Generator6strregEPKc(
-; CHECK-SAME: ptr [[THIS:%.*]], ptr [[S:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-SAME: ptr [[THIS:%.*]], ptr [[S:%.*]]) {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[TMP122:%.*]] = icmp eq ptr [[S]], null
 ; CHECK-NEXT:    br label [[BB184:%.*]]
 ; CHECK:       bb55:
 ; CHECK-NEXT:    ret i32 0
 ; CHECK:       bb88:
-; CHECK-NEXT:    br i1 [[TMP122]], label [[BB154:%.*]], label [[BB128:%.*]]
+; CHECK-NEXT:    br i1 poison, label [[BB154:%.*]], label [[BB128:%.*]]
 ; CHECK:       bb128:
-; CHECK-NEXT:    [[TMP138:%.*]] = call i32 @strcmp(ptr noundef nonnull dereferenceable(1) null, ptr noundef nonnull dereferenceable(1) [[S]])
-; CHECK-NEXT:    [[IFTMP_37_0_IN4:%.*]] = icmp eq i32 [[TMP138]], 0
-; CHECK-NEXT:    br i1 [[IFTMP_37_0_IN4]], label [[BB250:%.*]], label [[BB166:%.*]]
+; CHECK-NEXT:    br i1 poison, label [[BB250:%.*]], label [[BB166:%.*]]
 ; CHECK:       bb154:
 ; CHECK-NEXT:    br i1 false, label [[BB250]], label [[BB166]]
 ; CHECK:       bb166:
-; CHECK-NEXT:    [[TMP175:%.*]] = add i32 [[IDX_0:%.*]], 1
-; CHECK-NEXT:    [[TMP183:%.*]] = add nsw i32 [[I33_0:%.*]], 1
 ; CHECK-NEXT:    br label [[BB184]]
 ; CHECK:       bb184:
-; CHECK-NEXT:    [[I33_0]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[TMP183]], [[BB166]] ]
-; CHECK-NEXT:    [[IDX_0]] = phi i32 [ 0, [[ENTRY]] ], [ [[TMP175]], [[BB166]] ]
-; CHECK-NEXT:    [[TMP49:%.*]] = icmp slt i32 [[I33_0]], 0
-; CHECK-NEXT:    br i1 [[TMP49]], label [[BB88:%.*]], label [[BB55:%.*]]
+; CHECK-NEXT:    br i1 false, label [[BB88:%.*]], label [[BB55:%.*]]
 ; CHECK:       bb250:
-; CHECK-NEXT:    ret i32 [[IDX_0]]
+; CHECK-NEXT:    ret i32 poison
 ;
 entry:
   %s_addr.0 = select i1 false, ptr @.str9, ptr %s