If a global variable has a specified alignment that is less than the preferred

[oota-llvm.git] / lib / Target / README.txt

diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index 45da3ddb607a1532a3b24faeed0549895271b308..99616b47c841401f05ee90aa18dfa068a2794228 100644 (file)
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -392,34 +392,6 @@ PHI Slicing could be extended to do this.
 
 //===---------------------------------------------------------------------===//
 
-LSR should know what GPR types a target has from TargetData.  This code:
-
-volatile short X, Y; // globals
-
-void foo(int N) {
-  int i;
-  for (i = 0; i < N; i++) { X = i; Y = i*4; }
-}
-
-produces two near identical IV's (after promotion) on PPC/ARM:
-
-LBB1_2:
-       ldr r3, LCPI1_0
-       ldr r3, [r3]
-       strh r2, [r3]
-       ldr r3, LCPI1_1
-       ldr r3, [r3]
-       strh r1, [r3]
-       add r1, r1, #4
-       add r2, r2, #1   <- [0,+,1]
-       sub r0, r0, #1   <- [0,-,1]
-       cmp r0, #0
-       bne LBB1_2
-
-LSR should reuse the "+" IV for the exit test.
-
-//===---------------------------------------------------------------------===//
-
 Tail call elim should be more aggressive, checking to see if the call is
 followed by an uncond branch to an exit block.
 
@@ -2102,11 +2074,12 @@ for.end:                                          ; preds = %entry
 }
 
 This shouldn't need the ((zext (%n - 1)) + 1) game, and it should ideally fold
-the two memset's together. The issue with %n seems to stem from poor handling
-of the original loop.
+the two memset's together.
 
-To simplify this, we need SCEV to know that "n != 0" because of the dominating
-conditional.  That would turn the second memset into a simple memset of 'n'.
+The issue with the addition only occurs in 64-bit mode, and appears to be at
+least partially caused by Scalar Evolution not keeping its cache updated: it
+returns the "wrong" result immediately after indvars runs, but figures out the
+expected result if it is run from scratch on IR resulting from running indvars.
 
 //===---------------------------------------------------------------------===//
 
@@ -2265,4 +2238,23 @@ missed cases:
 
 //===---------------------------------------------------------------------===//
 
+define i1 @test1(i32 %x) nounwind {
+  %and = and i32 %x, 3
+  %cmp = icmp ult i32 %and, 2
+  ret i1 %cmp
+}
+
+Can be folded to (x & 2) == 0.
+
+define i1 @test2(i32 %x) nounwind {
+  %and = and i32 %x, 3
+  %cmp = icmp ugt i32 %and, 1
+  ret i1 %cmp
+}
+
+Can be folded to (x & 2) != 0.
 
+SimplifyDemandedBits shrinks the "and" constant to 2 but instcombine misses the
+icmp transform.
+
+//===---------------------------------------------------------------------===//