[IndVars] Use IRBuilder in eliminateTrunc [nfc-ish] (#70836)

Mostly a cleanup so that we don't need to manually emit instructions,
and can eagerly constant fold where relevant.

Author: preames

llvm/lib/Transforms/Utils/SimplifyIndVar.cpp

@@ -539,7 +539,8 @@ bool SimplifyIndvar::eliminateTrunc(TruncInst *TI) {
   for (auto *ICI : ICmpUsers) {
     bool IsSwapped = L->isLoopInvariant(ICI->getOperand(0));
     auto *Op1 = IsSwapped ? ICI->getOperand(0) : ICI->getOperand(1);
-    Instruction *Ext = nullptr;
+    IRBuilder<> Builder(ICI);
+    Value *Ext = nullptr;
     // For signed/unsigned predicate, replace the old comparison with comparison
     // of immediate IV against sext/zext of the invariant argument. If we can
     // use either sext or zext (i.e. we are dealing with equality predicate),
@@ -550,18 +551,18 @@ bool SimplifyIndvar::eliminateTrunc(TruncInst *TI) {
     if (IsSwapped) Pred = ICmpInst::getSwappedPredicate(Pred);
     if (CanUseZExt(ICI)) {
       assert(DoesZExtCollapse && "Unprofitable zext?");
-      Ext = new ZExtInst(Op1, IVTy, "zext", ICI);
+      Ext = Builder.CreateZExt(Op1, IVTy, "zext");
       Pred = ICmpInst::getUnsignedPredicate(Pred);
     } else {
       assert(DoesSExtCollapse && "Unprofitable sext?");
-      Ext = new SExtInst(Op1, IVTy, "sext", ICI);
+      Ext = Builder.CreateSExt(Op1, IVTy, "sext");
       assert(Pred == ICmpInst::getSignedPredicate(Pred) && "Must be signed!");
     }
     bool Changed;
     L->makeLoopInvariant(Ext, Changed);
     (void)Changed;
-    ICmpInst *NewICI = new ICmpInst(ICI, Pred, IV, Ext);
-    ICI->replaceAllUsesWith(NewICI);
+    auto *NewCmp = Builder.CreateICmp(Pred, IV, Ext);
+    ICI->replaceAllUsesWith(NewCmp);
     DeadInsts.emplace_back(ICI);
   }
 

llvm/test/Transforms/IndVarSimplify/X86/eliminate-trunc.ll

@@ -572,12 +572,11 @@ define void @test_13a(i32 %n) {
 ;
 ; CHECK-LABEL: @test_13a(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[ZEXT:%.*]] = zext i32 1024 to i64
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 2
-; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ne i64 [[IV]], 1024
 ; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret void
@@ -598,12 +597,11 @@ define void @test_13b(i32 %n) {
 ;
 ; CHECK-LABEL: @test_13b(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[ZEXT:%.*]] = zext i32 1024 to i64
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 2
-; CHECK-NEXT:    [[TMP0:%.*]] = icmp ult i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ult i64 [[IV]], 1024
 ; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret void
@@ -624,12 +622,11 @@ define void @test_13c(i32 %n) {
 ;
 ; CHECK-LABEL: @test_13c(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[ZEXT:%.*]] = zext i32 1024 to i64
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i64 [[IV]], 2
-; CHECK-NEXT:    [[TMP0:%.*]] = icmp ult i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp ult i64 [[IV]], 1024
 ; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret void
@@ -650,12 +647,11 @@ define void @test_13d(i32 %n) {
 ;
 ; CHECK-LABEL: @test_13d(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[SEXT:%.*]] = sext i32 1024 to i64
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
 ; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ -20, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
 ; CHECK-NEXT:    [[IV_NEXT]] = add nsw i64 [[IV]], 2
-; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i64 [[IV]], [[SEXT]]
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp slt i64 [[IV]], 1024
 ; CHECK-NEXT:    br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret void

llvm/test/Transforms/IndVarSimplify/ada-loops.ll

@@ -22,15 +22,14 @@ define void @kinds__sbytezero(ptr nocapture %a) nounwind {
 ; CHECK-NEXT:  bb.thread:
 ; CHECK-NEXT:    [[TMP46:%.*]] = getelementptr [256 x i32], ptr [[A]], i32 0, i32 0
 ; CHECK-NEXT:    store i32 0, ptr [[TMP46]], align 4
-; CHECK-NEXT:    [[SEXT:%.*]] = sext i8 127 to i32
 ; CHECK-NEXT:    br label [[BB:%.*]]
 ; CHECK:       bb:
 ; CHECK-NEXT:    [[INDVARS_IV:%.*]] = phi i32 [ [[INDVARS_IV_NEXT:%.*]], [[BB]] ], [ -128, [[BB_THREAD:%.*]] ]
 ; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nsw i32 [[INDVARS_IV]], 1
 ; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[INDVARS_IV_NEXT]], 128
 ; CHECK-NEXT:    [[TMP4:%.*]] = getelementptr [256 x i32], ptr [[A]], i32 0, i32 [[TMP3]]
 ; CHECK-NEXT:    store i32 0, ptr [[TMP4]], align 4
-; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i32 [[INDVARS_IV_NEXT]], [[SEXT]]
+; CHECK-NEXT:    [[TMP0:%.*]] = icmp eq i32 [[INDVARS_IV_NEXT]], 127
 ; CHECK-NEXT:    br i1 [[TMP0]], label [[RETURN:%.*]], label [[BB]]
 ; CHECK:       return:
 ; CHECK-NEXT:    ret void