Recommit "[InlineCost] Use TTI to check if GEP is free."

This recommits r292526 which is reverted in r292529 after fixing the test case.

The original summary:

Currently, a GEP is considered free only if its indices are all constant.
TTI::getGEPCost() can give target-specific more accurate analysis. TTI is
already used for the cost of many other instructions.

llvm-svn: 292570

1 files changed, 30 insertions, 0 deletions

diff --git a/llvm/test/Transforms/Inline/gep-cost.ll b/llvm/test/Transforms/Inline/gep-cost.ll
new file mode 100644
index 00000000000..442f7589176
--- /dev/null
+++ b/llvm/test/Transforms/Inline/gep-cost.ll
@@ -0,0 +1,30 @@
+; REQUIRES: asserts
+; RUN: opt -inline < %s -mtriple=aarch64--linux-gnu -mcpu=kryo -S -debug-only=inline-cost 2>&1 | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64--linux-gnu"
+
+define void @outer([4 x i32]* %ptr, i32 %i) {
+  call void @inner1([4 x i32]* %ptr, i32 %i)
+  call void @inner2([4 x i32]* %ptr, i32 %i)
+  ret void
+}
+; The gep in inner1() is reg+reg, which is a legal addressing mode for AArch64.
+; Thus, both the gep and ret can be simplified.
+; CHECK: Analyzing call of inner1
+; CHECK: NumInstructionsSimplified: 2
+; CHECK: NumInstructions: 2
+define void @inner1([4 x i32]* %ptr, i32 %i) {
+  %G = getelementptr inbounds [4 x i32], [4 x i32]* %ptr, i32 0, i32 %i
+  ret void
+}
+
+; The gep in inner2() is reg+imm+reg, which is not a legal addressing mode for 
+; AArch64.  Thus, only the ret can be simplified and not the gep.
+; CHECK: Analyzing call of inner2
+; CHECK: NumInstructionsSimplified: 1
+; CHECK: NumInstructions: 2
+define void @inner2([4 x i32]* %ptr, i32 %i) {
+  %G = getelementptr inbounds [4 x i32], [4 x i32]* %ptr, i32 1, i32 %i
+  ret void
+}