Infer alignment of loads and increase their alignment when we can tell they are

from the stack.  This allows us to compile stack-align.ll to:

_test:
	movsd	LCPI1_0, %xmm0
	movapd	%xmm0, %xmm1
***	andpd	4(%esp), %xmm1
	andpd	_G, %xmm0
	addsd	%xmm1, %xmm0
	movl	20(%esp), %eax
	movsd	%xmm0, (%eax)
	ret

instead of:

_test:
	movsd	LCPI1_0, %xmm0
**	movsd	4(%esp), %xmm1
**	andpd	%xmm0, %xmm1
	andpd	_G, %xmm0
	addsd	%xmm1, %xmm0
	movl	20(%esp), %eax
	movsd	%xmm0, (%eax)
	ret



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46401 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 22 insertions, 0 deletions

diff --git a/test/CodeGen/X86/stack-align.ll b/test/CodeGen/X86/stack-align.ll
new file mode 100644
index 0000000..1e6c2b2
--- /dev/null
+++ b/test/CodeGen/X86/stack-align.ll
@@ -0,0 +1,22 @@
+; RUN: llvm-as < %s | llc -relocation-model=static -mcpu=yonah | grep {andpd.*4(%esp), %xmm}
+
+; The double argument is at 4(esp) which is 16-byte aligned, allowing us to
+; fold the load into the andpd.
+
+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-f80:128:128"
+target triple = "i686-apple-darwin8"
+@G = external global double
+
+define void @test({ double, double }* byval  %z, double* %P) {
+entry:
+	%tmp = getelementptr { double, double }* %z, i32 0, i32 0		; <double*> [#uses=1]
+	%tmp1 = load double* %tmp, align 8		; <double> [#uses=1]
+	%tmp2 = tail call double @fabs( double %tmp1 )		; <double> [#uses=1]
+	%tmp3 = load double* @G, align 16		; <double> [#uses=1]
+	%tmp4 = tail call double @fabs( double %tmp3 )		; <double> [#uses=1]
+	%tmp6 = add double %tmp4, %tmp2		; <double> [#uses=1]
+	store double %tmp6, double* %P, align 8
+	ret void
+}
+
+declare double @fabs(double)