Teach instsimplify that X+Y>=X+Z is the same as Y>=Z if neither side overflows,

plus some variations of this.  According to my auto-simplifier this occurs a lot
but usually in combination with max/min idioms.  Because max/min aren't handled
yet this unfortunately doesn't have much effect in the testsuite.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125462 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstSimplify/compare.ll

@@ -0,0 +1,189 @@
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+target datalayout = "p:32:32"
+
+define i1 @ptrtoint() {
+; CHECK: @ptrtoint
+  %a = alloca i8
+  %tmp = ptrtoint i8* %a to i32
+  %r = icmp eq i32 %tmp, 0
+  ret i1 %r
+; CHECK: ret i1 false
+}
+
+define i1 @zext(i32 %x) {
+; CHECK: @zext
+  %e1 = zext i32 %x to i64
+  %e2 = zext i32 %x to i64
+  %r = icmp eq i64 %e1, %e2
+  ret i1 %r
+; CHECK: ret i1 true
+}
+
+define i1 @zext2(i1 %x) {
+; CHECK: @zext2
+  %e = zext i1 %x to i32
+  %c = icmp ne i32 %e, 0
+  ret i1 %c
+; CHECK: ret i1 %x
+}
+
+define i1 @zext3() {
+; CHECK: @zext3
+  %e = zext i1 1 to i32
+  %c = icmp ne i32 %e, 0
+  ret i1 %c
+; CHECK: ret i1 true
+}
+
+define i1 @sext(i32 %x) {
+; CHECK: @sext
+  %e1 = sext i32 %x to i64
+  %e2 = sext i32 %x to i64
+  %r = icmp eq i64 %e1, %e2
+  ret i1 %r
+; CHECK: ret i1 true
+}
+
+define i1 @sext2(i1 %x) {
+; CHECK: @sext2
+  %e = sext i1 %x to i32
+  %c = icmp ne i32 %e, 0
+  ret i1 %c
+; CHECK: ret i1 %x
+}
+
+define i1 @sext3() {
+; CHECK: @sext3
+  %e = sext i1 1 to i32
+  %c = icmp ne i32 %e, 0
+  ret i1 %c
+; CHECK: ret i1 true
+}
+
+define i1 @add(i32 %x, i32 %y) {
+; CHECK: @add
+  %l = lshr i32 %x, 1
+  %q = lshr i32 %y, 1
+  %r = or i32 %q, 1
+  %s = add i32 %l, %r
+  %c = icmp eq i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 false
+}
+
+define i1 @add2(i8 %x, i8 %y) {
+; CHECK: @add2
+  %l = or i8 %x, 128
+  %r = or i8 %y, 129
+  %s = add i8 %l, %r
+  %c = icmp eq i8 %s, 0
+  ret i1 %c
+; CHECK: ret i1 false
+}
+
+define i1 @add3(i8 %x, i8 %y) {
+; CHECK: @add3
+  %l = zext i8 %x to i32
+  %r = zext i8 %y to i32
+  %s = add i32 %l, %r
+  %c = icmp eq i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 %c
+}
+
+define i1 @add4(i32 %x, i32 %y) {
+; CHECK: @add4
+  %z = add nsw i32 %y, 1
+  %s1 = add nsw i32 %x, %y
+  %s2 = add nsw i32 %x, %z
+  %c = icmp slt i32 %s1, %s2
+  ret i1 %c
+; CHECK: ret i1 true
+}
+
+define i1 @add5(i32 %x, i32 %y) {
+; CHECK: @add5
+  %z = add nuw i32 %y, 1
+  %s1 = add nuw i32 %x, %z
+  %s2 = add nuw i32 %x, %y
+  %c = icmp ugt i32 %s1, %s2
+  ret i1 %c
+; CHECK: ret i1 true
+}
+
+define i1 @addpowtwo(i32 %x, i32 %y) {
+; CHECK: @addpowtwo
+  %l = lshr i32 %x, 1
+  %r = shl i32 1, %y
+  %s = add i32 %l, %r
+  %c = icmp eq i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 false
+}
+
+define i1 @or(i32 %x) {
+; CHECK: @or
+  %o = or i32 %x, 1
+  %c = icmp eq i32 %o, 0
+  ret i1 %c
+; CHECK: ret i1 false
+}
+
+define i1 @shl(i32 %x) {
+; CHECK: @shl
+  %s = shl i32 1, %x
+  %c = icmp eq i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 false
+}
+
+define i1 @lshr(i32 %x) {
+; CHECK: @lshr
+  %s = lshr i32 -1, %x
+  %c = icmp eq i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 false
+}
+
+define i1 @ashr(i32 %x) {
+; CHECK: @ashr
+  %s = ashr i32 -1, %x
+  %c = icmp eq i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 false
+}
+
+define i1 @select1(i1 %cond) {
+; CHECK: @select1
+  %s = select i1 %cond, i32 1, i32 0
+  %c = icmp eq i32 %s, 1
+  ret i1 %c
+; CHECK: ret i1 %cond
+}
+
+define i1 @select2(i1 %cond) {
+; CHECK: @select2
+  %x = zext i1 %cond to i32
+  %s = select i1 %cond, i32 %x, i32 0
+  %c = icmp ne i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 %cond
+}
+
+define i1 @select3(i1 %cond) {
+; CHECK: @select3
+  %x = zext i1 %cond to i32
+  %s = select i1 %cond, i32 1, i32 %x
+  %c = icmp ne i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 %cond
+}
+
+define i1 @select4(i1 %cond) {
+; CHECK: @select4
+  %invert = xor i1 %cond, 1
+  %s = select i1 %invert, i32 0, i32 1
+  %c = icmp ne i32 %s, 0
+  ret i1 %c
+; CHECK: ret i1 %cond
+}