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llvm-mirror/test/Transforms/CodeGenPrepare/AArch64/widen_switch.ll
Jun Bum Lim 4f195c2484 [CodeGenPrep] Skip merging empty case blocks
This is recommit of r287553 after fixing the invalid loop info after eliminating an empty block and unit test failures in AVR and WebAssembly :

Summary: Merging an empty case block into the header block of switch could cause ISel to add COPY instructions in the header of switch, instead of the case block, if the case block is used as an incoming block of a PHI. This could potentially increase dynamic instructions, especially when the switch is in a loop. I added a test case which was reduced from the benchmark I was targetting.

Reviewers: t.p.northover, mcrosier, manmanren, wmi, joerg, davidxl

Subscribers: joerg, qcolombet, danielcdh, hfinkel, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D22696

llvm-svn: 289988
2016-12-16 20:38:39 +00:00

96 lines
2.1 KiB
LLVM

;; AArch64 is arbitralily chosen as a 32/64-bit RISC representative to show the transform in all tests.
; RUN: opt < %s -codegenprepare -S -mtriple=aarch64-unknown-unknown | FileCheck %s --check-prefix=ARM64
; AArch64 widens to 32-bit.
define i32 @widen_switch_i16(i32 %a) {
entry:
%trunc = trunc i32 %a to i16
switch i16 %trunc, label %sw.default [
i16 1, label %sw.bb0
i16 -1, label %sw.bb1
]
sw.bb0:
br label %return
sw.bb1:
br label %return
sw.default:
br label %return
return:
%retval = phi i32 [ -1, %sw.default ], [ 0, %sw.bb0 ], [ 1, %sw.bb1 ]
ret i32 %retval
; ARM64-LABEL: @widen_switch_i16(
; ARM64: %0 = zext i16 %trunc to i32
; ARM64-NEXT: switch i32 %0, label %sw.default [
; ARM64-NEXT: i32 1, label %sw.bb0
; ARM64-NEXT: i32 65535, label %sw.bb1
}
; Widen to 32-bit from a smaller, non-native type.
define i32 @widen_switch_i17(i32 %a) {
entry:
%trunc = trunc i32 %a to i17
switch i17 %trunc, label %sw.default [
i17 10, label %sw.bb0
i17 -1, label %sw.bb1
]
sw.bb0:
br label %return
sw.bb1:
br label %return
sw.default:
br label %return
return:
%retval = phi i32 [ -1, %sw.default ], [ 0, %sw.bb0 ], [ 1, %sw.bb1 ]
ret i32 %retval
; ARM64-LABEL: @widen_switch_i17(
; ARM64: %0 = zext i17 %trunc to i32
; ARM64-NEXT: switch i32 %0, label %sw.default [
; ARM64-NEXT: i32 10, label %sw.bb0
; ARM64-NEXT: i32 131071, label %sw.bb1
}
; If the switch condition is a sign-extended function argument, then the
; condition and cases should be sign-extended rather than zero-extended
; because the sign-extension can be optimized away.
define i32 @widen_switch_i16_sext(i2 signext %a) {
entry:
switch i2 %a, label %sw.default [
i2 1, label %sw.bb0
i2 -1, label %sw.bb1
]
sw.bb0:
br label %return
sw.bb1:
br label %return
sw.default:
br label %return
return:
%retval = phi i32 [ -1, %sw.default ], [ 0, %sw.bb0 ], [ 1, %sw.bb1 ]
ret i32 %retval
; ARM64-LABEL: @widen_switch_i16_sext(
; ARM64: %0 = sext i2 %a to i32
; ARM64-NEXT: switch i32 %0, label %sw.default [
; ARM64-NEXT: i32 1, label %sw.bb0
; ARM64-NEXT: i32 -1, label %sw.bb1
}