Issue description:

SchedulerDAGInstrs::buildSchedGraph ignores dependencies between FixedStack
objects and byval parameters. So loading byval parameters from stack may be
inserted *before* it will be stored, since these operations are treated as
independent.

Fix:
Currently ARMTargetLowering::LowerFormalArguments saves byval registers with
FixedStack MachinePointerInfo. To fix the problem we need to store byval
registers with MachinePointerInfo referenced to first the "byval" parameter.

Also commit adds two new fields to the InputArg structure: Function's argument
index and InputArg's part offset in bytes relative to the start position of
Function's argument. E.g.: If function's argument is 128 bit width and it was
splitted onto 32 bit regs, then we got 4 InputArg structs with same arg index,
but different offset values. 

llvm-svn: 165616

1 files changed, 19 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/ARM/2012-10-04-FixedFrame-vs-byval.ll b/llvm/test/CodeGen/ARM/2012-10-04-FixedFrame-vs-byval.ll
new file mode 100644
index 00000000000..478048d0960
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/2012-10-04-FixedFrame-vs-byval.ll
@@ -0,0 +1,19 @@
+; RUN: llc < %s -mtriple=armv7-none-linux-gnueabi | FileCheck %s
+
+@.str = private unnamed_addr constant [12 x i8] c"val.a = %f\0A\00"
+%struct_t = type { double, double, double }
+@static_val = constant %struct_t { double 1.0, double 2.0, double 3.0 }
+
+declare i32 @printf(i8*, ...)
+
+; CHECK:     test_byval_usage_scheduling:
+; CHECK:       str     r3, [sp, #12]
+; CHECK:       str     r2, [sp, #8]
+; CHECK:       vldr    d16, [sp, #8]
+define void @test_byval_usage_scheduling(i32 %n1, i32 %n2, %struct_t* byval %val) nounwind {
+entry:
+  %a = getelementptr inbounds %struct_t* %val, i32 0, i32 0
+  %0 = load double* %a
+  %call = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([12 x i8]* @.str, i32 0, i32 0), double %0)
+  ret void
+}