[mips] Optimize stack pointer adjustments.
Instead of always using addu to adjust the stack pointer when the
size out is of the range of an addiu instruction, use subu so that
a smaller constant can be generated.
This can give savings of ~3 instructions whenever a function has a
a stack frame whose size is out of range of an addiu instruction.
This change may break some naive stack unwinders.
Partially resolves PR/26291.
Thanks to David Chisnall for reporting the issue.
Reviewers: dsanders, vkalintiris
Differential Review: http://reviews.llvm.org/D21321
llvm-svn: 272666
diff --git a/llvm/test/CodeGen/Mips/eh-dwarf-cfa.ll b/llvm/test/CodeGen/Mips/eh-dwarf-cfa.ll
index 6554974..c4019c7 100644
--- a/llvm/test/CodeGen/Mips/eh-dwarf-cfa.ll
+++ b/llvm/test/CodeGen/Mips/eh-dwarf-cfa.ll
@@ -13,6 +13,8 @@
%0 = call i8* @llvm.eh.dwarf.cfa(i32 0)
ret i8* %0
+; CHECK-LABEL: f1:
+
; CHECK: addiu $sp, $sp, -32
; CHECK: addiu $2, $sp, 32
}
@@ -24,10 +26,12 @@
%0 = call i8* @llvm.eh.dwarf.cfa(i32 0)
ret i8* %0
+; CHECK-LABEL: f2:
+
; check stack size (65536 + 8)
-; CHECK: lui $[[R0:[a-z0-9]+]], 65535
-; CHECK: addiu $[[R0]], $[[R0]], -8
-; CHECK: addu $sp, $sp, $[[R0]]
+; CHECK: lui $[[R0:[a-z0-9]+]], 1
+; CHECK: addiu $[[R0]], $[[R0]], 8
+; CHECK: subu $sp, $sp, $[[R0]]
; check return value ($sp + stack size)
; CHECK: lui $[[R1:[a-z0-9]+]], 1
@@ -46,6 +50,8 @@
%add = add i32 %1, %3
ret i32 %add
+; CHECK-LABEL: f3:
+
; CHECK: addiu $sp, $sp, -40
; check return value ($fp + stack size + $fp)
@@ -60,6 +66,8 @@
%0 = call i8* @llvm.eh.dwarf.cfa(i32 0)
ret i8* %0
+; CHECK-LABEL: f4:
+
; CHECK-MIPS64: daddiu $sp, $sp, -32
; CHECK-MIPS64: daddiu $2, $sp, 32
}
diff --git a/llvm/test/CodeGen/Mips/largeimm1.ll b/llvm/test/CodeGen/Mips/largeimm1.ll
index 01b25c1..b4d15f9 100644
--- a/llvm/test/CodeGen/Mips/largeimm1.ll
+++ b/llvm/test/CodeGen/Mips/largeimm1.ll
@@ -1,13 +1,19 @@
; RUN: llc -march=mipsel -relocation-model=pic < %s | FileCheck %s
-; CHECK: lui ${{[0-9]+}}, 49152
-; CHECK: lui ${{[0-9]+}}, 16384
define void @f() nounwind {
entry:
%a1 = alloca [1073741824 x i8], align 1
%arrayidx = getelementptr inbounds [1073741824 x i8], [1073741824 x i8]* %a1, i32 0, i32 1048676
call void @f2(i8* %arrayidx) nounwind
ret void
+; CHECK-LABEL: f:
+
+; CHECK: lui $[[R0:[a-z0-9]+]], 16384
+; CHECK: addiu $[[R1:[a-z0-9]+]], $[[R0]], 24
+; CHECK: subu $sp, $sp, $[[R1]]
+
+; CHECK: lui $[[R2:[a-z0-9]+]], 16384
+; CHECK: addu ${{[0-9]+}}, $sp, $[[R2]]
}
declare void @f2(i8*)
diff --git a/llvm/test/CodeGen/Mips/largeimmprinting.ll b/llvm/test/CodeGen/Mips/largeimmprinting.ll
index f45320d..f27e114 100644
--- a/llvm/test/CodeGen/Mips/largeimmprinting.ll
+++ b/llvm/test/CodeGen/Mips/largeimmprinting.ll
@@ -10,21 +10,19 @@
define void @f() nounwind {
entry:
-; 32: lui $[[R0:[0-9]+]], 65535
-; 32: addiu $[[R0]], $[[R0]], -24
-; 32: addu $sp, $sp, $[[R0]]
-; 32: lui $[[R1:[0-9]+]], 1
-; 32: addu $[[R1]], $sp, $[[R1]]
-; 32: sw $ra, 20($[[R1]])
-; 64: daddiu $[[R0:[0-9]+]], $zero, 1
-; 64: dsll $[[R0]], $[[R0]], 48
-; 64: daddiu $[[R0]], $[[R0]], -1
-; 64: dsll $[[R0]], $[[R0]], 16
-; 64: daddiu $[[R0]], $[[R0]], -32
-; 64: daddu $sp, $sp, $[[R0]]
-; 64: lui $[[R1:[0-9]+]], 1
-; 64: daddu $[[R1]], $sp, $[[R1]]
-; 64: sd $ra, 24($[[R1]])
+; 32: lui $[[R0:[0-9]+]], 1
+; 32: addiu $[[R0]], $[[R0]], 24
+; 32: subu $sp, $sp, $[[R0]]
+; 32: lui $[[R1:[0-9]+]], 1
+; 32: addu $[[R1]], $sp, $[[R1]]
+; 32: sw $ra, 20($[[R1]])
+
+; 64: lui $[[R0:[0-9]+]], 1
+; 64: daddiu $[[R0]], $[[R0]], 32
+; 64: dsubu $sp, $sp, $[[R0]]
+; 64: lui $[[R1:[0-9]+]], 1
+; 64: daddu $[[R1]], $sp, $[[R1]]
+; 64: sd $ra, 24($[[R1]])
%agg.tmp = alloca %struct.S1, align 1
%tmp = getelementptr inbounds %struct.S1, %struct.S1* %agg.tmp, i32 0, i32 0, i32 0