[llvm] r335020 - [SimplifyIndVars] Eliminate redundant truncs
Max Kazantsev via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 18 21:48:34 PDT 2018
Author: mkazantsev
Date: Mon Jun 18 21:48:34 2018
New Revision: 335020
URL: http://llvm.org/viewvc/llvm-project?rev=335020&view=rev
Log:
[SimplifyIndVars] Eliminate redundant truncs
This patch adds logic to deal with the following constructions:
%iv = phi i64 ...
%trunc = trunc i64 %iv to i32
%cmp = icmp <pred> i32 %trunc, %invariant
Replacing it with
%iv = phi i64 ...
%cmp = icmp <pred> i64 %iv, sext/zext(%invariant)
In case if it is legal. Specifically, if `%iv` has signed comparison users, it is
required that `sext(trunc(%iv)) == %iv`, and if it has unsigned comparison
uses then we require `zext(trunc(%iv)) == %iv`. The current implementation
bails if `%trunc` has other uses than `icmp`, but in theory we can handle more
cases here (e.g. if the user of trunc is bitcast).
Differential Revision: https://reviews.llvm.org/D47928
Reviewed By: reames
Added:
llvm/trunk/test/Transforms/IndVarSimplify/eliminate-trunc.ll
Modified:
llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp
llvm/trunk/test/Transforms/IndVarSimplify/ada-loops.ll
llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll
Modified: llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp?rev=335020&r1=335019&r2=335020&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyIndVar.cpp Mon Jun 18 21:48:34 2018
@@ -81,6 +81,7 @@ namespace {
bool replaceIVUserWithLoopInvariant(Instruction *UseInst);
bool eliminateOverflowIntrinsic(CallInst *CI);
+ bool eliminateTrunc(TruncInst *TI);
bool eliminateIVUser(Instruction *UseInst, Instruction *IVOperand);
bool makeIVComparisonInvariant(ICmpInst *ICmp, Value *IVOperand);
void eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand);
@@ -494,6 +495,93 @@ bool SimplifyIndvar::eliminateOverflowIn
return true;
}
+bool SimplifyIndvar::eliminateTrunc(TruncInst *TI) {
+ // It is always legal to replace
+ // icmp <pred> i32 trunc(iv), n
+ // with
+ // icmp <pred> i64 sext(trunc(iv)), sext(n), if pred is signed predicate.
+ // Or with
+ // icmp <pred> i64 zext(trunc(iv)), zext(n), if pred is unsigned predicate.
+ // Or with either of these if pred is an equality predicate.
+ //
+ // If we can prove that iv == sext(trunc(iv)) or iv == zext(trunc(iv)) for
+ // every comparison which uses trunc, it means that we can replace each of
+ // them with comparison of iv against sext/zext(n). We no longer need trunc
+ // after that.
+ //
+ // TODO: Should we do this if we can widen *some* comparisons, but not all
+ // of them? Sometimes it is enough to enable other optimizations, but the
+ // trunc instruction will stay in the loop.
+ Value *IV = TI->getOperand(0);
+ Type *IVTy = IV->getType();
+ const SCEV *IVSCEV = SE->getSCEV(IV);
+ const SCEV *TISCEV = SE->getSCEV(TI);
+
+ // Check if iv == zext(trunc(iv)) and if iv == sext(trunc(iv)). If so, we can
+ // get rid of trunc
+ bool DoesSExtCollapse = false;
+ bool DoesZExtCollapse = false;
+ if (IVSCEV == SE->getSignExtendExpr(TISCEV, IVTy))
+ DoesSExtCollapse = true;
+ if (IVSCEV == SE->getZeroExtendExpr(TISCEV, IVTy))
+ DoesZExtCollapse = true;
+
+ // If neither sext nor zext does collapse, it is not profitable to do any
+ // transform. Bail.
+ if (!DoesSExtCollapse && !DoesZExtCollapse)
+ return false;
+
+ // Collect users of the trunc that look like comparisons against invariants.
+ // Bail if we find something different.
+ SmallVector<ICmpInst *, 4> ICmpUsers;
+ for (auto *U : TI->users()) {
+ if (ICmpInst *ICI = dyn_cast<ICmpInst>(U)) {
+ if (ICI->getOperand(0) == TI && L->isLoopInvariant(ICI->getOperand(1))) {
+ assert(L->contains(ICI->getParent()) && "LCSSA form broken?");
+ // If we cannot get rid of trunc, bail.
+ if (ICI->isSigned() && !DoesSExtCollapse)
+ return false;
+ if (ICI->isUnsigned() && !DoesZExtCollapse)
+ return false;
+ // For equality, either signed or unsigned works.
+ ICmpUsers.push_back(ICI);
+ } else
+ return false;
+ } else
+ return false;
+ }
+
+ // Replace all comparisons against trunc with comparisons against IV.
+ for (auto *ICI : ICmpUsers) {
+ auto *Op1 = ICI->getOperand(1);
+ Instruction *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),
+ // then prefer zext as a more canonical form.
+ // TODO: If we see a signed comparison which can be turned into unsigned,
+ // we can do it here for canonicalization purposes.
+ if (ICI->isUnsigned() || (ICI->isEquality() && DoesZExtCollapse)) {
+ assert(DoesZExtCollapse && "Unprofitable zext?");
+ Ext = new ZExtInst(Op1, IVTy, "zext", ICI);
+ } else {
+ assert(DoesSExtCollapse && "Unprofitable sext?");
+ Ext = new SExtInst(Op1, IVTy, "sext", ICI);
+ }
+ bool Changed;
+ L->makeLoopInvariant(Ext, Changed);
+ (void)Changed;
+ ICmpInst *NewICI = new ICmpInst(ICI, ICI->getPredicate(), IV, Ext);
+ ICI->replaceAllUsesWith(NewICI);
+ DeadInsts.emplace_back(ICI);
+ }
+
+ // Trunc no longer needed.
+ TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
+ DeadInsts.emplace_back(TI);
+ return true;
+}
+
/// Eliminate an operation that consumes a simple IV and has no observable
/// side-effect given the range of IV values. IVOperand is guaranteed SCEVable,
/// but UseInst may not be.
@@ -518,6 +606,10 @@ bool SimplifyIndvar::eliminateIVUser(Ins
if (eliminateOverflowIntrinsic(CI))
return true;
+ if (auto *TI = dyn_cast<TruncInst>(UseInst))
+ if (eliminateTrunc(TI))
+ return true;
+
if (eliminateIdentitySCEV(UseInst, IVOperand))
return true;
Modified: llvm/trunk/test/Transforms/IndVarSimplify/ada-loops.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/ada-loops.ll?rev=335020&r1=335019&r2=335020&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/ada-loops.ll (original)
+++ llvm/trunk/test/Transforms/IndVarSimplify/ada-loops.ll Mon Jun 18 21:48:34 2018
@@ -10,12 +10,17 @@
; don't check that phis are "folded together" because that is a job
; for loop strength reduction. But indvars must remove sext, zext, and add i8.
;
-; CHECK-NOT: {{sext|zext|add i8}}
; ModuleID = 'ada.bc'
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-n8:16:32"
target triple = "i686-pc-linux-gnu"
+; CHECK-LABEL: @kinds__sbytezero
+; CHECK: bb.thread:
+; CHECK: sext
+; CHECK: bb:
+; CHECK-NOT: {{sext i8|zext i8|add i8|trunc}}
+
define void @kinds__sbytezero([256 x i32]* nocapture %a) nounwind {
bb.thread:
%tmp46 = getelementptr [256 x i32], [256 x i32]* %a, i32 0, i32 0 ; <i32*> [#uses=1]
@@ -36,6 +41,8 @@ return: ; preds = %bb
ret void
}
+; CHECK-LABEL: @kinds__ubytezero
+
define void @kinds__ubytezero([256 x i32]* nocapture %a) nounwind {
bb.thread:
%tmp35 = getelementptr [256 x i32], [256 x i32]* %a, i32 0, i32 0 ; <i32*> [#uses=1]
Added: llvm/trunk/test/Transforms/IndVarSimplify/eliminate-trunc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/eliminate-trunc.ll?rev=335020&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/eliminate-trunc.ll (added)
+++ llvm/trunk/test/Transforms/IndVarSimplify/eliminate-trunc.ll Mon Jun 18 21:48:34 2018
@@ -0,0 +1,486 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -indvars -S < %s | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; General case: without extra knowledge, trunc cannot be eliminated.
+define void @test_00(i64 %start, i32 %n) {
+;
+; CHECK-LABEL: @test_00(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[START:%.*]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV]], 1
+; CHECK-NEXT: [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT: br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp slt i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+
+define void @test_01(i32 %n) {
+;
+; CHECK-LABEL: @test_01(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[N:%.*]] 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]], 1
+; CHECK-NEXT: [[TMP0:%.*]] = icmp slt i64 [[IV]], [[SEXT]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp slt i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Max value at which we can eliminate trunc: SINT_MAX - 1.
+define void @test_02(i32 %n) {
+;
+; CHECK-LABEL: @test_02(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[N:%.*]] to i64
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 2147483646, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT: [[TMP0:%.*]] = icmp slt i64 [[IV]], [[SEXT]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 2147483646, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp slt i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; If we start from SINT_MAX then the predicate is always false.
+define void @test_03(i32 %n) {
+;
+; CHECK-LABEL: @test_03(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: br i1 false, label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [2147483647, %entry], [%iv.next, %loop]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp slt i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Minimum value at which we can apply the transform: SINT_MIN + 1.
+define void @test_04(i32 %n) {
+;
+; CHECK-LABEL: @test_04(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[N:%.*]] to i64
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ -2147483647, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add nsw i64 [[IV]], 1
+; CHECK-NEXT: [[TMP0:%.*]] = icmp slt i64 [[IV]], [[SEXT]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ -2147483647, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp slt i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; FIXME: Harmful LFTR should be thrown away.
+define void @test_05(i32 %n) {
+;
+; CHECK-LABEL: @test_05(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[N:%.*]], 1
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ -2147483648, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add nsw i64 [[IV]], 1
+; CHECK-NEXT: [[LFTR_WIDEIV:%.*]] = trunc i64 [[IV_NEXT]] to i32
+; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne i32 [[LFTR_WIDEIV]], [[TMP0]]
+; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ -2147483648, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp slt i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Trunc changes the actual value of the IV, so it is invalid to remove it: SINT_MIN - 1.
+define void @test_06(i32 %n) {
+;
+; CHECK-LABEL: @test_06(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ -2147483649, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT: [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT: br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ -2147483649, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp slt i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; General case: without extra knowledge, trunc cannot be eliminated.
+define void @test_00_unsigned(i64 %start, i32 %n) {
+; CHECK-LABEL: @test_00_unsigned(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[START:%.*]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add i64 [[IV]], 1
+; CHECK-NEXT: [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT: br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp ult i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; FIXME: Harmful LFTR should be thrown away.
+define void @test_01_unsigned(i32 %n) {
+; CHECK-LABEL: @test_01_unsigned(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[N:%.*]], 1
+; 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]], 1
+; CHECK-NEXT: [[LFTR_WIDEIV:%.*]] = trunc i64 [[IV_NEXT]] to i32
+; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne i32 [[LFTR_WIDEIV]], [[TMP0]]
+; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp ult i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Max value at which we can eliminate trunc: UINT_MAX - 1.
+define void @test_02_unsigned(i32 %n) {
+; CHECK-LABEL: @test_02_unsigned(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[N:%.*]] to i64
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 4294967294, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT: [[TMP0:%.*]] = icmp ult i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 4294967294, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp ult i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; If we start from UINT_MAX then the predicate is always false.
+define void @test_03_unsigned(i32 %n) {
+; CHECK-LABEL: @test_03_unsigned(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: br i1 false, label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 4294967295, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp ult i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Minimum value at which we can apply the transform: UINT_MIN.
+define void @test_04_unsigned(i32 %n) {
+; CHECK-LABEL: @test_04_unsigned(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[N:%.*]], 1
+; 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]], 1
+; CHECK-NEXT: [[LFTR_WIDEIV:%.*]] = trunc i64 [[IV_NEXT]] to i32
+; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne i32 [[LFTR_WIDEIV]], [[TMP0]]
+; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp ult i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Start from 1.
+define void @test_05_unsigned(i32 %n) {
+; CHECK-LABEL: @test_05_unsigned(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[N:%.*]] to i64
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 1, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT: [[TMP0:%.*]] = icmp ult i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 1, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp ult i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Trunc changes the actual value of the IV, so it is invalid to remove it: UINT_MIN - 1.
+define void @test_06_unsigned(i32 %n) {
+; CHECK-LABEL: @test_06_unsigned(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ -1, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add nsw i64 [[IV]], 1
+; CHECK-NEXT: [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT: br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ -1, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp ult i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Do not eliminate trunc if it is used by something different from icmp.
+define void @test_07(i32* %p, i32 %n) {
+; CHECK-LABEL: @test_07(
+; CHECK-NEXT: entry:
+; 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]], 1
+; CHECK-NEXT: [[NARROW_IV:%.*]] = trunc i64 [[IV]] to i32
+; CHECK-NEXT: store i32 [[NARROW_IV]], i32* [[P:%.*]]
+; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[NARROW_IV]], [[N:%.*]]
+; CHECK-NEXT: br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ store i32 %narrow.iv, i32* %p
+ %cmp = icmp slt i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Check that we can eliminate both signed and unsigned compare.
+define void @test_08(i32 %n) {
+; CHECK-LABEL: @test_08(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[N:%.*]] to i64
+; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[N]] to i64
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ 1, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT: [[TMP0:%.*]] = icmp slt i64 [[IV]], [[SEXT]]
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ult i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT: [[CMP:%.*]] = and i1 [[TMP0]], [[TMP1]]
+; CHECK-NEXT: br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 1, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp1 = icmp slt i32 %narrow.iv, %n
+ %cmp2 = icmp ult i32 %narrow.iv, %n
+ %cmp = and i1 %cmp1, %cmp2
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Widen NE as unsigned.
+define void @test_09(i32 %n) {
+; CHECK-LABEL: @test_09(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[ZEXT:%.*]] = zext i32 [[N:%.*]] 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]], 1
+; CHECK-NEXT: [[TMP0:%.*]] = icmp ne i64 [[IV]], [[ZEXT]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %cmp = icmp ne i32 %narrow.iv, %n
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
+
+; Widen NE as signed.
+define void @test_10(i32 %n) {
+; CHECK-LABEL: @test_10(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[N:%.*]] to i64
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i64 [ -100, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
+; CHECK-NEXT: [[IV_NEXT]] = add nuw nsw i64 [[IV]], 1
+; CHECK-NEXT: [[TMP0:%.*]] = icmp ne i64 [[IV]], [[SEXT]]
+; CHECK-NEXT: [[NEGCMP:%.*]] = icmp slt i64 [[IV]], -10
+; CHECK-NEXT: [[CMP:%.*]] = and i1 [[TMP0]], [[NEGCMP]]
+; CHECK-NEXT: br i1 [[CMP]], label [[LOOP]], label [[EXIT:%.*]]
+; CHECK: exit:
+; CHECK-NEXT: ret void
+;
+entry:
+ br label %loop
+loop:
+ %iv = phi i64 [ -100, %entry ], [ %iv.next, %loop ]
+ %iv.next = add i64 %iv, 1
+ %narrow.iv = trunc i64 %iv to i32
+ %trunccmp = icmp ne i32 %narrow.iv, %n
+ %negcmp = icmp slt i64 %iv, -10
+ %cmp = and i1 %trunccmp, %negcmp
+ br i1 %cmp, label %loop, label %exit
+exit:
+ ret void
+}
Modified: llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll?rev=335020&r1=335019&r2=335020&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll (original)
+++ llvm/trunk/test/Transforms/IndVarSimplify/widen-loop-comp.ll Mon Jun 18 21:48:34 2018
@@ -332,12 +332,12 @@ define i32 @test10(i32 %v) {
br label %loop
loop:
+; CHECK: [[WIDE_V:%[a-z0-9]+]] = sext i32 %v to i64
; CHECK: loop:
; CHECK: %indvars.iv = phi i64 [ %indvars.iv.next, %loop ], [ 0, %entry ]
; CHECK: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
; CHECK: [[MUL:%[a-z0-9]+]] = mul nsw i64 %indvars.iv, -1
-; CHECK: [[MUL_TRUNC:%[a-z0-9]+]] = trunc i64 [[MUL]] to i32
-; CHECK: [[CMP:%[a-z0-9]+]] = icmp eq i32 [[MUL_TRUNC]], %v
+; CHECK: [[CMP:%[a-z0-9]+]] = icmp eq i64 [[MUL]], [[WIDE_V]]
; CHECK: call void @consume.i1(i1 [[CMP]])
%i = phi i32 [ 0, %entry ], [ %i.inc, %loop ]
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