Enhance ComputeMaskedBits to know that aligned frameindexes
have their low bits set to zero. This allows us to optimize
out explicit stack alignment code like in stack-align.ll:test4 when
it is redundant.
Doing this causes the code generator to start turning FI+cst into
FI|cst all over the place, which is general goodness (that is the
canonical form) except that various pieces of the code generator
don't handle OR aggressively. Fix this by introducing a new
SelectionDAG::isBaseWithConstantOffset predicate, and using it
in places that are looking for ADD(X,CST). The ARM backend in
particular was missing a lot of addressing mode folding opportunities
around OR.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125470 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/X86/stack-align.ll b/test/CodeGen/X86/stack-align.ll
index 8ca0b12..793c026 100644
--- a/test/CodeGen/X86/stack-align.ll
+++ b/test/CodeGen/X86/stack-align.ll
@@ -7,7 +7,7 @@
target triple = "i686-apple-darwin8"
@G = external global double
-define void @test({ double, double }* byval %z, double* %P) {
+define void @test({ double, double }* byval %z, double* %P) nounwind {
entry:
%tmp3 = load double* @G, align 16 ; <double> [#uses=1]
%tmp4 = tail call double @fabs( double %tmp3 ) ; <double> [#uses=1]
@@ -21,14 +21,14 @@
ret void
}
-define void @test2() alignstack(16) {
+define void @test2() alignstack(16) nounwind {
entry:
; CHECK: andl{{.*}}$-16, %esp
ret void
}
; Use a call to force a spill.
-define <2 x double> @test3(<2 x double> %x, <2 x double> %y) alignstack(32) {
+define <2 x double> @test3(<2 x double> %x, <2 x double> %y) alignstack(32) nounwind {
entry:
; CHECK: andl{{.*}}$-32, %esp
call void @test2()
@@ -38,3 +38,14 @@
declare double @fabs(double)
+; The pointer is already known aligned, so and x,-16 is eliminable.
+define i32 @test4() nounwind {
+entry:
+ %buffer = alloca [2048 x i8], align 16
+ %0 = ptrtoint [2048 x i8]* %buffer to i32
+ %and = and i32 %0, -16
+ ret i32 %and
+; CHECK: test4:
+; CHECK-NOT: and
+; CHECK: ret
+}