From aef3d140b74013c5042e730194fef48c01bfd27e Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Thu, 1 Jul 2010 03:49:38 +0000 Subject: Teach fast-isel to avoid loading a value from memory when it's already available in a register. This is pretty primitive, but it reduces the number of instructions in common testcases by 4%. llvm-svn: 107380 --- llvm/test/CodeGen/X86/fast-isel-loads.ll | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) create mode 100644 llvm/test/CodeGen/X86/fast-isel-loads.ll (limited to 'llvm/test/CodeGen/X86/fast-isel-loads.ll') diff --git a/llvm/test/CodeGen/X86/fast-isel-loads.ll b/llvm/test/CodeGen/X86/fast-isel-loads.ll new file mode 100644 index 00000000000..2fbb46c0b9f --- /dev/null +++ b/llvm/test/CodeGen/X86/fast-isel-loads.ll @@ -0,0 +1,23 @@ +; RUN: llc -march=x86-64 -O0 -asm-verbose=false < %s | FileCheck %s + +; Fast-isel shouldn't reload the argument values from the stack. + +; CHECK: foo: +; CHECK-NEXT: movq %rdi, -8(%rsp) +; CHECK-NEXT: movq %rsi, -16(%rsp) +; CHECK-NEXT: movsd 128(%rsi,%rdi,8), %xmm0 +; CHECK-NEXT: ret + +define double @foo(i64 %x, double* %p) nounwind { +entry: + %x.addr = alloca i64, align 8 ; [#uses=2] + %p.addr = alloca double*, align 8 ; [#uses=2] + store i64 %x, i64* %x.addr + store double* %p, double** %p.addr + %tmp = load i64* %x.addr ; [#uses=1] + %tmp1 = load double** %p.addr ; [#uses=1] + %add = add nsw i64 %tmp, 16 ; [#uses=1] + %arrayidx = getelementptr inbounds double* %tmp1, i64 %add ; [#uses=1] + %tmp2 = load double* %arrayidx ; [#uses=1] + ret double %tmp2 +} -- cgit v1.2.3