From 8799552d28163b539bfcdedb065082002f2ad6c6 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo@fhahn.com>
Date: Wed, 18 Nov 2020 11:25:39 +0000
Subject: [PATCH] [ConstraintElimination] Decompose add nuw/sub nuw.

Make use of the more flexible constraint handling added in
a8a79c90699a7ae9dee07daf7281cbbd592bf6ea to decompose add nuw/sub nuw.
---
 .../Scalar/ConstraintElimination.cpp          | 14 +++++++
 .../ConstraintElimination/add-nuw.ll          | 40 +++++++++----------
 .../ConstraintElimination/sub-nuw.ll          | 26 ++++++------
 3 files changed, 47 insertions(+), 33 deletions(-)

diff --git a/lib/Transforms/Scalar/ConstraintElimination.cpp b/lib/Transforms/Scalar/ConstraintElimination.cpp
index 2ae913ce8f0..251faa0b182 100644
--- a/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -57,6 +57,20 @@ static SmallVector<std::pair<int64_t, Value *>, 4> decompose(Value *V) {
              nullptr},
             {1, GEP->getPointerOperand()}};
   }
+
+  Value *Op0;
+  Value *Op1;
+  ConstantInt *CI;
+  if (match(V, m_NUWAdd(m_Value(Op0), m_ConstantInt(CI))))
+    return {{CI->getSExtValue(), nullptr}, {1, Op0}};
+  if (match(V, m_NUWAdd(m_Value(Op0), m_Value(Op1))))
+    return {{0, nullptr}, {1, Op0}, {1, Op1}};
+
+  if (match(V, m_NUWSub(m_Value(Op0), m_ConstantInt(CI))))
+    return {{-1 * CI->getSExtValue(), nullptr}, {1, Op0}};
+  if (match(V, m_NUWSub(m_Value(Op0), m_Value(Op1))))
+    return {{0, nullptr}, {1, Op0}, {1, Op1}};
+
   return {{0, nullptr}, {1, V}};
 }
 
diff --git a/test/Transforms/ConstraintElimination/add-nuw.ll b/test/Transforms/ConstraintElimination/add-nuw.ll
index 2e2b3213a7a..17925166748 100644
--- a/test/Transforms/ConstraintElimination/add-nuw.ll
+++ b/test/Transforms/ConstraintElimination/add-nuw.ll
@@ -11,16 +11,16 @@ define void @test.not.uge.ult(i8 %start, i8 %low, i8 %high) {
 ; CHECK-NEXT:    ret void
 ; CHECK:       if.end:
 ; CHECK-NEXT:    [[T_0:%.*]] = icmp ult i8 [[START]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_0]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_1:%.*]] = add nuw i8 [[START]], 1
 ; CHECK-NEXT:    [[T_1:%.*]] = icmp ult i8 [[START_1]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_1]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_2:%.*]] = add nuw i8 [[START]], 2
 ; CHECK-NEXT:    [[T_2:%.*]] = icmp ult i8 [[START_2]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_2]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_3:%.*]] = add nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[T_3:%.*]] = icmp ult i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_3]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_4:%.*]] = add nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[C_4:%.*]] = icmp ult i8 [[START_4]], [[HIGH]]
 ; CHECK-NEXT:    call void @use(i1 [[C_4]])
@@ -62,19 +62,19 @@ define void @test.not.uge.ule(i8 %start, i8 %low, i8 %high) {
 ; CHECK-NEXT:    ret void
 ; CHECK:       if.end:
 ; CHECK-NEXT:    [[T_0:%.*]] = icmp ule i8 [[START]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_0]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_1:%.*]] = add nuw i8 [[START]], 1
 ; CHECK-NEXT:    [[T_1:%.*]] = icmp ule i8 [[START_1]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_1]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_2:%.*]] = add nuw i8 [[START]], 2
 ; CHECK-NEXT:    [[T_2:%.*]] = icmp ule i8 [[START_2]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_2]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_3:%.*]] = add nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[T_3:%.*]] = icmp ule i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_3]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_4:%.*]] = add nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[T_4:%.*]] = icmp ule i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_4]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_5:%.*]] = add nuw i8 [[START]], 5
 ; CHECK-NEXT:    [[C_5:%.*]] = icmp ule i8 [[START_5]], [[HIGH]]
 ; CHECK-NEXT:    call void @use(i1 [[C_5]])
@@ -121,19 +121,19 @@ define void @test.not.uge.ugt(i8 %start, i8 %low, i8 %high) {
 ; CHECK-NEXT:    ret void
 ; CHECK:       if.end:
 ; CHECK-NEXT:    [[F_0:%.*]] = icmp ugt i8 [[START]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_0]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_1:%.*]] = add nuw i8 [[START]], 1
 ; CHECK-NEXT:    [[F_1:%.*]] = icmp ugt i8 [[START_1]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_1]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_2:%.*]] = add nuw i8 [[START]], 2
 ; CHECK-NEXT:    [[F_2:%.*]] = icmp ugt i8 [[START_2]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_2]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_3:%.*]] = add nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[F_3:%.*]] = icmp ugt i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_3]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_4:%.*]] = add nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[F_4:%.*]] = icmp ugt i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_4]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_5:%.*]] = add nuw i8 [[START]], 5
 ; CHECK-NEXT:    [[C_5:%.*]] = icmp ugt i8 [[START_5]], [[HIGH]]
 ; CHECK-NEXT:    call void @use(i1 [[C_5]])
@@ -184,16 +184,16 @@ define void @test.not.uge.uge(i8 %start, i8 %low, i8 %high) {
 ; CHECK-NEXT:    ret void
 ; CHECK:       if.end:
 ; CHECK-NEXT:    [[F_0:%.*]] = icmp ugt i8 [[START]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_0]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_1:%.*]] = add nuw i8 [[START]], 1
 ; CHECK-NEXT:    [[F_1:%.*]] = icmp uge i8 [[START_1]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_1]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_2:%.*]] = add nuw i8 [[START]], 2
 ; CHECK-NEXT:    [[F_2:%.*]] = icmp uge i8 [[START_2]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_2]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_3:%.*]] = add nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[F_3:%.*]] = icmp uge i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_3]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_4:%.*]] = add nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[C_4:%.*]] = icmp uge i8 [[START_4]], [[HIGH]]
 ; CHECK-NEXT:    call void @use(i1 [[C_4]])
@@ -252,10 +252,10 @@ define void @test.decompose.nonconst(i8 %a, i8 %b, i8 %c, i8 %d) {
 ; CHECK:       if.then.2:
 ; CHECK-NEXT:    [[ADD_0:%.*]] = add nuw i8 [[A]], [[B]]
 ; CHECK-NEXT:    [[T_0:%.*]] = icmp uge i8 [[ADD_0]], [[C]]
-; CHECK-NEXT:    call void @use(i1 [[T_0]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[ADD_1:%.*]] = add nuw i8 [[A]], [[A]]
 ; CHECK-NEXT:    [[T_1:%.*]] = icmp uge i8 [[ADD_0]], [[C]]
-; CHECK-NEXT:    call void @use(i1 [[T_1]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[ADD_2:%.*]] = add nuw i8 [[A]], [[D:%.*]]
 ; CHECK-NEXT:    [[C_4:%.*]] = icmp uge i8 [[ADD_2]], [[C]]
 ; CHECK-NEXT:    call void @use(i1 [[C_4]])
diff --git a/test/Transforms/ConstraintElimination/sub-nuw.ll b/test/Transforms/ConstraintElimination/sub-nuw.ll
index f440bf7bbff..7912c3c9355 100644
--- a/test/Transforms/ConstraintElimination/sub-nuw.ll
+++ b/test/Transforms/ConstraintElimination/sub-nuw.ll
@@ -20,10 +20,10 @@ define void @test.not.uge.ult(i8 %start, i8 %low, i8 %high) {
 ; CHECK-NEXT:    call void @use(i1 [[T_2]])
 ; CHECK-NEXT:    [[START_3:%.*]] = sub nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[T_3:%.*]] = icmp ult i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_3]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_4:%.*]] = sub nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[C_4:%.*]] = icmp ult i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_4]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    ret void
 ;
 entry:
@@ -68,16 +68,16 @@ define void @test.not.uge.ule(i8 %start, i8 %low, i8 %high) {
 ; CHECK-NEXT:    call void @use(i1 [[T_1]])
 ; CHECK-NEXT:    [[START_2:%.*]] = sub nuw i8 [[START]], 2
 ; CHECK-NEXT:    [[T_2:%.*]] = icmp ule i8 [[START_2]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_2]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_3:%.*]] = sub nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[T_3:%.*]] = icmp ule i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_3]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_4:%.*]] = sub nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[T_4:%.*]] = icmp ule i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[T_4]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    [[START_5:%.*]] = sub nuw i8 [[START]], 5
 ; CHECK-NEXT:    [[C_5:%.*]] = icmp ule i8 [[START_5]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_5]])
+; CHECK-NEXT:    call void @use(i1 true)
 ; CHECK-NEXT:    ret void
 ;
 entry:
@@ -127,16 +127,16 @@ define void @test.not.uge.ugt(i8 %start, i8 %low, i8 %high) {
 ; CHECK-NEXT:    call void @use(i1 [[F_1]])
 ; CHECK-NEXT:    [[START_2:%.*]] = sub nuw i8 [[START]], 2
 ; CHECK-NEXT:    [[F_2:%.*]] = icmp ugt i8 [[START_2]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_2]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_3:%.*]] = sub nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[F_3:%.*]] = icmp ugt i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_3]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_4:%.*]] = sub nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[F_4:%.*]] = icmp ugt i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_4]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_5:%.*]] = sub nuw i8 [[START]], 5
 ; CHECK-NEXT:    [[C_5:%.*]] = icmp ugt i8 [[START_5]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_5]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    ret void
 ;
 entry:
@@ -193,13 +193,13 @@ define void @test.not.uge.uge(i8 %start, i8 %low, i8 %high) {
 ; CHECK-NEXT:    call void @use(i1 [[F_2]])
 ; CHECK-NEXT:    [[START_3:%.*]] = sub nuw i8 [[START]], 3
 ; CHECK-NEXT:    [[F_3:%.*]] = icmp uge i8 [[START_3]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[F_3]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_4:%.*]] = sub nuw i8 [[START]], 4
 ; CHECK-NEXT:    [[C_4:%.*]] = icmp uge i8 [[START_4]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_4]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    [[START_5:%.*]] = sub nuw i8 [[START]], 5
 ; CHECK-NEXT:    [[C_5:%.*]] = icmp uge i8 [[START_5]], [[HIGH]]
-; CHECK-NEXT:    call void @use(i1 [[C_5]])
+; CHECK-NEXT:    call void @use(i1 false)
 ; CHECK-NEXT:    ret void
 ;
 entry: